Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

Abstract

We develop a new deconvolution method to recover the precise Crab Nebula image taken by the Hitomi HXT, suppressing the artifact due to the bright Crab pulsar. We extend the Richardson–Lucy method, introducing two components corresponding to the nebula and pulsar with regularization for smoothness and flux, respectively, and performing simultaneous deconvolution of multi-pulse-phase images. The structures, including the torus and jets, seen in the deconvolved nebula image at the lowest energy band of 3.6–15 keV appear consistent with those identified in the high-resolution Chandra X-ray image. Above 15 keV, we confirm NuSTAR’s findings that the nebula size decreases in higher energy bands. We find that the north-east side of the nebula is fainter in higher energy bands. Our deconvolution method is applicable for any telescope images of faint diffuse objects containing a bright point source.

DOI： 10.1093/pasj/psae008

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2676572

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Publishing type：Research paper (scientific journal)  

Low-temperature detectors often use mechanical coolers as part of the cooling chain in order to reach sub-Kelvin operating temperatures. The microphonic noise caused by the mechanical coolers is a general and inherent issue for these detectors. We have observed this effect in the ground test data obtained with the Resolve instrument to be flown on the XRISM satellite. Resolve is a cryogenic X-ray microcalorimeter spectrometer with a required energy resolution of 7 eV at 6 keV. Five mechanical coolers are used to cool from ambient temperature to ∼ 4 K: four two-stage Stirling coolers (STC) driven nominally at 15 Hz and a Joule–Thomson cooler (JTC) driven nominally at 52 Hz. In 2019, we operated the flight-model instrument for two weeks, in which we also obtained accelerometer data inside the cryostat at a low-temperature stage (He tank). X-ray detector and accelerometer data were obtained continuously while changing the JTC drive frequency, which produced a unique data set for investigating how the vibration from the cryocoolers propagates to the detector. In the detector noise spectra, we observed harmonics of both STCs and JTC. More interestingly, we also observed the low (< 20 Hz) frequency beat between the 4th JTC and 14th STC harmonics and the 7th JTC and the 23–24th STC harmonics. We present here a description and interpretation of these measurements.

DOI： 10.1007/s10909-022-02935-1

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Publishing type：Research paper (scientific journal)   Publisher：SPIE-Intl Soc Optical Eng  

DOI： 10.1117/1.jatis.9.2.025004

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Publishing type：Research paper (scientific journal)  

Resolve is a payload hosting an x-ray microcalorimeter detector operated at 50 mK in the x-ray imaging and spectroscopy mission. It is currently under development as part of an international collaboration and is planned to be launched in 2023. A primary technical concern is the microvibration interference in the sensitive microcalorimeter detector caused by the spacecraft bus components. We conducted a series of verification tests in 2021 to 2022 on the ground, the results of which are reported here. We defined the microvibration interface between the spacecraft and the Resolve instrument. In the instrument-level test, the flight-model hardware was tested against the interface level by injecting it with microvibrations and evaluating the instrument response using the 50 mK stage temperature stability, adiabatic demagnetization refrigerator magnet current consumption rate, and detector noise spectra. We found strong responses when injecting microvibration at 1/4200, 380, and 610 Hz. In the former two cases, the beat between the injected frequency and cryocooler frequency harmonics were observed in the detector noise spectra. In the spacecraft-level test, the acceleration and instrument responses were measured with and without suspension of the entire spacecraft. The reaction wheels (RWs) and inertial reference units (IRUs), two major sources of microvibration among the bus components, were operated. In conclusion, the observed responses of Resolve are within the acceptable levels in the nominal operational range of the RWs and IRUs. There is no evidence that the resultant energy resolution degradation is beyond the current allocation of noise budget.

DOI： 10.1117/1.JATIS.9.1.014003

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.nima.2022.167975

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Publishing type：Research paper (scientific journal)   Publisher：SPIE-Intl Soc Optical Eng  

DOI： 10.1117/1.jatis.8.4.044001

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2630654

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2628772

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2629705

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2626537

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Publishing type：Research paper (international conference proceedings)  

Resolve is a payload hosting an x-ray microcalorimeter detector operated at 50 mK in the X-Ray Imaging and Spectroscopy Mission (XRISM), which is currently under development by an international collaboration and is planned to be launched in 2023. One of the technical concerns is the micro-vibration interference to the sensitive microcalorimeter detector by the spacecraft bus components. We verified this in a series of the ground tests in 2021–2022, the results of which are reported here. We defined the micro-vibration interface between the spacecraft and the Resolve instrument. In the instrument-level test, we tested the flight-model hardware against the interface level by injecting micro-vibration using vibrators and evaluated the instrument response using the 50 mK stage temperature stability, the ADR magnet current consumption rate, and the detector noise spectra. We found the strong responses when injecting micro-vibration at ∼200, 380, and 610 Hz. In the former two cases, the beat among the injected frequency and the cryocooler frequency harmonics are also observed in the detector noise spectra. In the spacecraft-level test, we measured the acceleration and the instrument responses with and without suspending the entire spacecraft. The reaction wheels and the inertial reference units, two major sources of micro-vibration among the bus components, were operated. We found that the observed Resolve responses are within acceptable levels.

DOI： 10.1117/12.2629782

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

The Resolve instrument onboard the XRISM satellite is equipped with 6 x 6 x-ray microcalorimeter detectors aiming at an energy resolution of 7 eV (FWHM) at 5.9 keV. It is currently under development by an international collaboration and will be launched in 2023. The detectors are operated at 50 mK, which is achieved by a combination of four Stirling coolers (STC), one Joule-Thomson cooler (JTC), three-stage adiabatic demagnetization refrigerators, and superfluid helium inside the dewar. The cryocoolers (STC and JTC) are significant sources of microphonic noise against the detector performance. To understand and characterize the microphonic propagation, we monitored the level of vibration throughout the ground instrument-level tests in 2019-2022, yielding a rich and unique data set of the accelerometers and the detector at 50 mK amounting to 1720 hours (6.2 Ms). In this article, we report the result of classifying thermal and non-thermal microcalorimeter noise, distinguishing the origin of the noise, and the method for optimizing the cooler drive frequency that minimizes the effect of the noise originating from the cooler.

DOI： 10.1117/12.2629773

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Publishing type：Research paper (scientific journal)   Publisher：Elsevier BV  

DOI： 10.1016/j.astropartphys.2020.102529

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Publishing type：Research paper (scientific journal)   Publisher：SPIE-Intl Soc Optical Eng  

DOI： 10.1117/1.jatis.7.1.014001

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2560319

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2560928

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2562193

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2560772

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Publishing type：Research paper (international conference proceedings)   Publisher：SPIE  

DOI： 10.1117/12.2561890

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Publishing type：Research paper (international conference proceedings)  

The X-Ray Imaging and Spectroscopy Mission (XRISM) is the successor to the 2016 Hitomi mission that ended prematurely. Like Hitomi, the primary science goals are to examine astrophysical problems with precise high-resolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. XRISM carries a 6 x 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly and a co-aligned X-ray CCD camera that covers the same energy band over a large field of view. XRISM utilizes Hitomi heritage, but all designs were reviewed. The attitude and orbit control system were improved in hardware and software. The number of star sensors were increased from two to three to improve coverage and robustness in onboard attitude determination and to obtain a wider field of view sun sensor. The fault detection, isolation, and reconfiguration (FDIR) system was carefully examined and reconfigured. Together with a planned increase of ground support stations, the survivability of the spacecraft is significantly improved.

DOI： 10.1117/12.2565812

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.75.1.0_523

CiNii Research

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Authorship：Lead author   Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPIE-Intl Soc Optical Eng  

Carbon-fiber-reinforced plastic (CFRP) has a higher strength-to-weight ratio and forming flexibility than metals, making it suitable for fabricating lightweight X-ray mirrors. However, CFRP has the disadvantages of print-through and deformation due to moisture absorption, which have prevented its use in optical mirrors. To expand the application of CFRP, we studied the formation of a moisture barrier layer on CFRP substrates. We formed a flattening layer a few micrometers thick on a CFRP substrate, following which we coated the substrate with SiOx as a moisture barrier. The effect of moisture absorption was then evaluated using accelerated aging tests. We found that the diffusivity of the CFRP substrate at 60°C and a relative humidity of 100% was ∼2 × 10-6 mm2 h-1, which is 1/500th that of the barrier-less substrate. In the tests, the moisture absorption rate increased after ∼800 h. As we observed cracks on the flattening layer after 600 h, the rate increase could be associated with these cracks. Considering the damage to the barrier layer, we propose a modified model for the time profile, which is congruent with the observed time profile of the moisture content.

DOI： 10.1117/1.jatis.5.4.044001

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Language：English   Publishing type：Research paper (scientific journal)  

X-ray polarimetry in astronomy has not been exploited well, despite its importance. The recent innovation of instruments is changing this situation. We focus on a complementary metal-oxide-semiconductor (CMOS) pixel detector with small pixel size and employ it as an x-ray photoelectron tracking polarimeter. The CMOS detector we employ is developed by GPixel Inc. and has a pixel size of 2.5 μm × 2.5 μm. Although it is designed for visible light, we succeed in detecting x-ray photons with an energy resolution of 176 eV (FWHM) at 5.9 keV at room temperature and the atmospheric condition. We measure the x-ray detection efficiency and polarimetry sensitivity by irradiating polarized monochromatic x-rays at BL20B2 in SPring-8, the synchrotron radiation facility in Japan. We obtain modulation factors of 7.63 % ± 0.07 % and 15.5 % ± 0.4 % at 12.4 and 24.8 keV, respectively. It demonstrates that this sensor can be used as an x-ray imaging spectrometer and polarimeter with the highest spatial resolution ever tested.

DOI： 10.1117/1.JATIS.5.3.035002

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We present the results from the Hitomi Soft Gamma-ray Detector (SGD) observation of the Crab nebula. The main part of SGD is a Compton camera, which in addition to being a spectrometer, is capable of measuring polarization of gamma-ray photons. The Crab nebula is one of the brightest X-ray / gamma-ray sources on the sky, and, the only source from which polarized X-ray photons have been detected. SGD observed the Crab nebula during the initial test observation phase of Hitomi. We performed the data analysis of the SGD observation, the SGD background estimation and the SGD Monte Carlo simulations, and, successfully detected polarized gamma-ray emission from the Crab nebula with only about 5 ks exposure time. The obtained polarization fraction of the phase-integrated Crab emission (sum of pulsar and nebula emissions) is (22.1% +/- 10.6%), and, the polarization angle is 110.degrees 7 + 13.degrees 2 /-13.degrees 0 in the energy range of 60-160 keV (The errors correspond to the 1 sigma deviation). The confidence level of the polarization detection was 99.3%. The polarization angle measured by SGD is about one sigma deviation with the projected spin axis of the pulsar, 124.degrees 0 +/- 0.degrees 1.

DOI： 10.1093/pasj/psy118

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psy027

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Language：English  

© The Authors. The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.

DOI： 10.1117/1.JATIS.4.2.021402

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Publishing type：Research paper (scientific journal)  

© The Author(s) 2017. Published by Oxford University Press on behalf of the Astronomical Society of Japan. To search for giant X-ray pulses correlated with the giant radio pulses (GRPs) from the Crab pulsar, we performed a simultaneous observation of the Crab pulsar with the X-ray satellite Hitomi in the 2-300 keV band and the Kashima NICT radio telescope in the 1.4-1.7 GHz band with a net exposure of about 2 ks on 2016 March 25, just before the loss of the Hitomi mission. The timing performance of the Hitomi instruments was confirmed to meet the timing requirement and about 1000 and 100 GRPs were simultaneously observed at the main pulse and inter-pulse phases, respectively, and we found no apparent correlation between the giant radio pulses and the X-ray emission in either the main pulse or inter-pulse phase. All variations are within the 2 σ fluctuations of the X-ray fluxes at the pulse peaks, and the 3 σ upper limits of variations of main pulse or inter-pulse GRPs are 22% or 80% of the peak flux in a 0.20 phase width, respectively, in the 2-300 keV band. The values for main pulse or inter-pulse GRPs become 25% or 110%, respectively, when the phase width is restricted to the 0.03 phase. Among the upper limits from the Hitomi satellite, those in the 4.5-10 keV and 70-300 keV bands are obtained for the first time, and those in other bands are consistent with previous reports. Numerically, the upper limits of the main pulse and inter-pulse GRPs in the 0.20 phase width are about (2.4 and 9.3) × 10−11 erg cm−2, respectively. No significant variability in pulse profiles implies that the GRPs originated from a local place within the magnetosphere. Although the number of photon-emitting particles should temporarily increase to account for the brightening of the radio emission, the results do not statistically rule out variations correlated with the GRPs, because the possible X-ray enhancement may appear due to a >0.02% brightening of the pulse-peak flux under such conditions.

DOI： 10.1093/pasj/psx083

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psx072

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We describe the in-orbit performance of the soft X-ray imaging system consisting of the Soft X-ray Telescope and the Soft X-ray Imager aboard Hitomi. Verification and calibration of imaging and spectroscopic performance are carried out, making the best use of the limited data of less than three weeks. Basic performance, including a large field of view of 38' x 38', is verified with the first-light image of the Perseus cluster of galaxies. Amongst the small number of observed targets, the on-minus-off pulse image for the out-of-time events of the Crab pulsar enables us to measure the half-power diameter of the telescope as similar to 1.'3. The average energy resolution measured with the onboard calibration source events at 5.89 keV is 179 +/- 3 eV in full width at half maximum. Light leak and crosstalk issues affected the effective exposure time and the effective area, respectively, because all the observations were performed before optimizing an observation schedule and the parameters for the dark-level calculation. Screening the data affected by these two issues, we measure the background level to be 5.6 x 10(-6) counts s(-1) arcmin(-2) cm(-2) in the energy band of 5-12 keV, which is seven times lower than that of the Suzaku XIS-BI.

DOI： 10.1093/pasj/psx116

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psx151

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psx156

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psx127

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psx138

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psy004

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psx154

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Publishing type：Research paper (scientific journal)   Publisher：Oxford University Press (OUP)  

DOI： 10.1093/pasj/psx147

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present a uniform broadband X-ray (0.5-100.0 keV) spectral analysis of 12 Swift/Burst Alert Telescope selected Compton-thick (log N-H cm(-2) >= 24) active galactic nuclei (CTAGNs) observed with Suzaku. The Suzaku data of three objects are published here for the first time. We fit the Suzaku and Swift spectra with models utilizing an analytic reflection code and those utilizing the Monte-Carlo-based model from an AGN torus by Ikeda et al. The main results are as follows: (1) The estimated intrinsic luminosity of a CTAGN strongly depends on the model; applying Compton scattering to the transmitted component in an analytic model may largely overestimate the intrinsic luminosity at large column densities. (2) Unabsorbed reflection components are commonly observed, suggesting that the tori are clumpy. (3) Most of CTAGNs show small scattering fractions (<0.5%), implying a buried AGN nature. (4) Comparison with the results obtained for Compton-thin AGNs suggests that the properties of these CTAGNs can be understood as a smooth extension from Compton-thin AGNs with heavier obscuration; we find no evidence that the bulk of the population of hard-X-ray-selected CTAGNs are different from less obscured objects.

DOI： 10.3847/1538-4357/aaa47c

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPIE  

We designed depth-graded multilayers, so-called supermirrors, with platinum/carbon (Pt/C) layer pairs for the Hard X-Ray Telescope (HXT) that was on-board the sixth Japanese X-Ray Astronomy Satellite Hitomi (ASTRO-H). The HXT has multinested thin foil optics, and the grazing angles of the X-ray mirrors are 0.07 to 0.27 deg. Supermirrors for HXTs are designed to provide a broad energy response (up to 80 keV) for astronomical requests. Under practical boundary conditions, we establish a block method applying empirical rules to maximize the integrated reflectivity. We fabricated Pt/C supermirrors using a DC magnetron sputtering system. The reflectivity of the mirrors was measured in a synchrotron radiation facility, SPring-8. We describe the design method for the supermirrors and our results.

DOI： 10.1117/1.JATIS.4.1.011209

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Language：English   Publishing type：Research paper (scientific journal)  

© 2018 The Authors. We present x-ray characteristics of the Hard X-ray Telescopes (HXTs) on board the Hitomi (ASTRO-H) satellite. Measurements were conducted at the SPring-8 BL20B2 beamline and the ISAS/JAXA 27-m beamline. The angular resolution defined by a half-power diameter was 1.9′ (HXT-1) and 2.1′ (HXT-2) at 8 keV, 1.9′ at 30 keV, and 1.8′ at 50 keV. The effective area was found to be 620cm2 at 8 keV, 178cm2 at 30 keV, and 82cm2 at 50 keV per mirror module. Although the angular resolutions were slightly worse than the requirement (1.7′), the effective areas sufficiently exceeded the requirements of 150cm2 at 30 keV and 55cm2 at 50 keV. The off-axis measurements of the effective areas resulted in the field of view being 6.1′ at 50 keV, 7.7′ at 30 keV, and 9.7′ at 8 keV in diameter. We confirmed that the main component of the stray x-ray light was significantly reduced by mounting the precollimator as designed. Detailed analysis of the data revealed that the angular resolution was degraded mainly by figure errors of mirror foils, and the angular resolution is completely explained by the figure errors, positioning errors of the foils, and conical approximation of the foil shape. We found that the effective areas were ∼80% of the designed values below 40 keV, whereas they steeply decline above 40 keV and become only ∼50%. We investigated this abrupt decline and found that neither the error of the multilayer design nor the errors of the incident angles induced by the positioning errors of the foils can be the cause. The reflection profile of each foil pair from the defocused image strongly suggests that the figure errors of the foils probably bring about the reduction in the effective areas at higher energies.

DOI： 10.1117/1.JATIS.4.1.011210

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：SPIE  

Hitomi (ASTRO-H) carries two Hard X-ray Telescopes (HXTs), which can focus x-rays up to 80 keV. Combined with the hard x-ray imagers (HXIs) that detect the focused x-rays, imaging spectroscopy in the high-energy band from 5 to 80 keV is made possible. We studied characteristics of HXTs after the launch, such as the encircled energy function (EEF) and the effective area using the data of a Crab observation. The half power diameters (HPDs) in the 5- to 80-keV band evaluated from the EEFs are 1.59 arcmin for HXT-1 and 1.65 arcmin for HXT-2. Those are consistent with the HPDs measured with ground experiments when uncertainties are taken into account. We can conclude that there is no significant change in the characteristics of the HXTs before and after the launch. The off-axis angle of the aim point from the optical axis is evaluated to be &lt
0.5 arcmin for both HXT-1 and HXT-2. The best-fit parameters for the Crab spectrum obtained with the HXT-HXI system are consistent with the canonical values.

DOI： 10.1117/1.JATIS.4.1.011212

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Publishing type：Research paper (international conference proceedings)  

We have proposed a new type of X-ray interferometer called Multi Image X-ray Interferometer Module (MIXIM) consisting simply of a grating and an X-ray spectral imaging detector. The baseline concept of MIXIM is a slit camera to obtain the profile of X-ray sources, but aim to get a sub-arcsecond resolution. For that purpose, to avoid blurring of the image by diffraction is a key, and we select X-ray events of which energy satisfies the interferometric condition called Talbot effect. Stacking the images (X-ray interferometric fringes) with the period of the grating is another point of the method, which provides the self image of a grating slit convolved with the profile of the X-ray source. We started an experiment with a micro focus X-ray source, 4.8 μm pitch grating, and an SOI type X-ray detector XRPIX2b with a pixel size of 30 μm. The stacked self image was obtained with a magnification factor of 4.4. We, however, need finer positional resolution for the detector to obtain the self image to a parallel beam, for which the magnification factor must be 1. We thus focused on small pixel size CMOS sensors developed for visible light. We irradiated X-rays to one of such CMOS sensors GSENSE5130 with a pixel size of 4.25 μm, and found enough capability to detect X-rays, i.e., FWHM of 207 eV at 5.9 keV at room temperature. We then employed this sensor and performed an experiment at a 200 m beam line of BL20B2 in the synchrotron facility SPring8. Using a grating with a pitch of 4.8 μm and an opening fraction of f=0.5, we obtained the self image of the grating at the detector distance from the grating of 23 cm and 46 cm and the X-ray energy of 12.4 keV. We also performed an experiment using a 9.6 μm f = 0.2 grating with a detector-grating distance of 92 cm, and obtained higher contrast image of the grating. Note that the slit width of 2.4 μm at 46 cm corresponds to 1.1′′, while that of 1.9 μm at 92 cm does 0.43′′. We suggest several format of possible MIXIM missions, including MIXIM-S for very small satellite of 50cm size, MIXIM-P for parasite use of nominal X-ray observatory employing grazing X-ray telescopes with a focal length of 10 m, and MIXIM-Z in which the grating-detector distance of 100 m is acquired by formation flight or free fryers to yield 0.01" level resolution.

DOI： 10.1117/12.2314181

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

The ASTRO-H mission was designed and developed through an international collaboration of JAXA, NASA, ESA, and the CSA. It was successfully launched on February 17, 2016, and then named Hitomi. During the in-orbit verification phase, the on-board observational instruments functioned as expected. The intricate coolant and refrigeration systems for soft X-ray spectrometer (SXS, a quantum micro-calorimeter) and soft X-ray imager (SXI, an X-ray CCD) also functioned as expected. However, on March 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. These errors led to a fatal event: the loss of the solar panels on the Hitomi mission. The X-ray Astronomy Recovery Mission (or, XARM) is proposed to regain the key scientific advances anticipated by the international collaboration behind Hitomi. XARM will recover this science in the shortest time possible by focusing on one of the main science goals of Hitomi, "Resolving astrophysical problems by precise high-resolution X-ray spectroscopy".(1) This decision was reached after evaluating the performance of the instruments aboard Hitomi and the mission's initial scientific results, and considering the landscape of planned international X-ray astrophysics missions in 2020's and 2030's.Hitomi opened the door to high-resolution spectroscopy in the X-ray universe. It revealed a number of discrepancies between new observational results and prior theoretical predictions. Yet, the resolution pioneered by Hitomi is also the key to answering these and other fundamental questions. The high spectral resolution realized by XARM will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. XARM has therefore been given a broad scientific charge: "Revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects". To fulfill this charge, four categories of science objectives that were defined for Hitomi will also be pursued by XARM; these include (1) Structure formation of the Universe and evolution of clusters of galaxies; (2) Circulation history of baryonic matters in the Universe; (3) Transport and circulation of energy in the Universe; (4) New science with unprecedented high resolution X-ray spectroscopy. In order to achieve these scientific objectives, XARM will carry a 6 x 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly, and an aligned X-ray CCD camera covering the same energy band and a wider field of view. This paper introduces the science objectives, mission concept, and observing plan of XARM.

DOI： 10.1117/12.2309455

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

The metal abundance of the hot plasma that permeates galaxy clusters represents the accumulation of heavy elements produced by billions of supernovae(1). Therefore, X-ray spectroscopy of the intracluster medium provides an opportunity to investigate the nature of supernova explosions integrated over cosmic time. In particular, the abundance of the iron-peak elements (chromium, manganese, iron and nickel) is key to understanding how the progenitors of typical type Ia supernovae evolve and explode(2-6). Recent X-ray studies of the intracluster medium found that the abundance ratios of these elements differ substantially from those seen in the Sun(7-11), suggesting differences between the nature of type Ia supernovae in the clusters and in the Milky Way. However, because the K-shell transition lines of chromium and manganese are weak and those of iron and nickel are very close in photon energy, highresolution spectroscopy is required for an accurate determination of the abundances of these elements. Here we report observations of the Perseus cluster, with statistically significant detections of the resonance emission from chromium, manganese and nickel. Our measurements, combined with the latest atomic models, reveal that these elements have near-solar abundance ratios with respect to iron, in contrast to previous claims. Comparison between our results and modern nucleosynthesis calculations(12-14) disfavours the hypothesis that type Ia supernova progenitors are exclusively white dwarfs with masses well below the Chandrasekhar limit (about 1.4 times the mass of the Sun). The observed abundance pattern of the iron-peak elements can be explained by taking into account a combination of near-and sub-Chandrasekhar-mass type Ia supernova systems, adding to the mounting evidence that both progenitor types make a substantial contribution to cosmic chemical enrichment(5,15,16).

DOI： 10.1038/nature24301

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

X-ray spectroscopy with Hitomi was expected to resolve the origin of the faint unidentified E approximate to 3.5 keV emission line reported in several low-resolution studies of various massive systems, such as galaxies and clusters, including the Perseus cluster. We have analyzed the Hitomi first-light observation of the Perseus cluster. The emission line expected for Perseus based on the XMM-Newton signal from the large cluster sample under the dark matter decay scenario is too faint to be detectable in the Hitomi data. However, the previously reported 3.5 keV flux from Perseus was anomalously high compared to the sample-based prediction. We find no unidentified line at the reported high flux level. Taking into account the XMM measurement uncertainties for this region, the inconsistency with Hitomi is at a 99% significance for a broad dark matter line and at 99.7% for a narrow line from the gas. We do not find anomalously high fluxes of the nearby faint K line or the Ar satellite line that were proposed as explanations for the earlier 3.5 keV detections. We do find a hint of a broad excess near the energies of high-n transitions of S XVI (E similar or equal to 3.44 keV rest-frame)-a possible signature of charge exchange in the molecular nebula and another proposed explanation for the unidentified line. While its energy is consistent with XMM pn detections, it is unlikely to explain the MOS signal. A confirmation of this interesting feature has to wait for a more sensitive observation with a future calorimeter experiment.

DOI： 10.3847/2041-8213/aa61fa

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

In this paper, we report the results of an X-ray monitoring campaign on the heavily obscured Seyfert galaxy, Markarian 3, carried out between the fall of 2014 and the spring of 2015 with NuSTAR, Suzaku and XMM-Newton. The hard X-ray spectrum of Markarian 3 is variable on all the time-scales probed by our campaign, down to a few days. The observed continuum variability is due to an intrinsically variable primary continuum seen in transmission through a large, but still Compton-thin column density (N-H similar to 0.8-1.1 x 10(24) cm(-2)). If arranged in a spherical-toroidal geometry, the Compton scattering matter has an opening angle a parts per thousand integral 66A degrees, and is seen at a grazing angle through its upper rim (inclination angle a parts per thousand integral 70A degrees). We report a possible occultation event during the 2014 campaign. If the torus is constituted by a system of clouds sharing the same column density, this event allows us to constrain their number (17 +/- 5) and individual column density, [a parts per thousand integral (4.9 +/- 1.5) x 10(22) cm(-2)]. The comparison of IR and X-ray spectroscopic results with state-of-the art 'torus' models suggests that at least two-thirds of the X-ray obscuring gas volume might be located within the dust sublimation radius. We report also the discovery of an ionized absorber, characterized by variable resonant absorption lines due to He- and H-like iron. This discovery lends support to the idea that moderate column density absorbers could be due to clouds evaporated at the outer surface of the torus, possibly accelerated by the radiation pressure due to the central AGN emission leaking through the patchy absorber.

DOI： 10.1093/mnras/stw1033

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arXiv

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：NATURE PUBLISHING GROUP  

Clusters of galaxies are the most massive gravitationally bound objects in the Universe and are still forming. They are thus important probes(1) of cosmological parameters and many astrophysical processes. However, knowledge of the dynamics of the pervasive hot gas, the mass of which is much larger than the combined mass of all the stars in the cluster, is lacking. Such knowledge would enable insights into the injection of mechanical energy by the central supermassive black hole and the use of hydrostatic equilibrium for determining cluster masses. X-rays from the core of the Perseus cluster are emitted by the 50-million-kelvin diffuse hot plasma filling its gravitational potential well. The active galactic nucleus of the central galaxy NGC 1275 is pumping jetted energy into the surrounding intracluster medium, creating buoyant bubbles filled with relativistic plasma. These bubbles probably induce motions in the intracluster medium and heat the inner gas, preventing runaway radiative cooling-a process known as active galactic nucleus feedback(2-6). Here we report X-ray observations of the core of the Perseus cluster, which reveal a remarkably quiescent atmosphere in which the gas has a line-of-sight velocity dispersion of 164 +/- 10 kilometres per second in the region 30-60 kiloparsecs from the central nucleus. A gradient in the line-of-sight velocity of 150 +/- 70 kilometres per second is found across the 60-kiloparsec image of the cluster core. Turbulent pressure support in the gas is four per cent of the thermodynamic pressure, with large-scale shear at most doubling this estimate. We infer that a total cluster mass determined from hydrostatic equilibrium in a central region would require little correction for turbulent pressure.

DOI： 10.1038/nature18627

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© The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI. We fabricated x-ray mirrors from carbon-fiber-reinforced plastic with a tightly nested design for x-ray satellites, using a replication method for the surfaces. We studied the effects of print-through on the mirror surface as a function of curing temperature. With room temperature curing, the root-mean-square value of the surface error was 0.8 nm. The reflectivity was measured using 8-keV x-rays, and the roughness was calculated as 0.5 nm by model fitting - comparable to that of the ASTRO-H/HXT mirror. We verified the long-term stability of the mirror surface over 6 months. We fabricated Wolter type-I quadrant-shell mirrors with a diameter of 200 mm and performed x-ray measurements at BL20B2 in the SPring-8 synchrotron radiation facility. We obtained reflection images of the mirrors using a 20-keV x-ray spot beam with a slit size of 10 x 1 mm in the radial and circumferential directions, respectively. The averaged half-power diameter (HPD) of the images in one mirror was 1.2 arc min in the circumferential center of the mirror and 3.0 arc min at the edge. In the spot images with a smaller slit size of 10 x 0.2 mm, we achieved an HPD of 0.38 arc min in the best case.

DOI： 10.1117/1.JATIS.2.1.014002

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.71.2.0_369

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We report a new sample of obscured active galactic nuclei (AGNs) selected from the XMM-Newton serendipitous source and AKARI point-source catalogs. We match X-ray sources with infrared (18 and 90 mu m) sources located at vertical bar b vertical bar &gt; 10 degrees to create a sample consisting of 173 objects. Their optical classifications and absorption column densities measured by X-ray spectra are compiled and study efficient selection criteria to find obscured AGNs. We apply the criteria (1) X-ray hardness ratio defined by using the 2-4.5 keV and 4.5-12 keV bands &gt; -0.1 and (2) EPIC-PN count rate (CR) in the 0.2-12 keV to infrared flux ratio CR/F-90 &lt; 0.1 or CR/F-18 &lt; 1, where F-18 and F-90 are infrared fluxes at 18 and 90 mu m in Jy, respectively, to search for obscured AGNs. X-ray spectra of 48 candidates, for which no X-ray results have been published, are analyzed and X-ray evidence for the presence of obscured AGNs such as a convex shape X-ray spectrum indicative of absorption of N-H similar to 10(22-24) cm(-2), a very flat continuum, or a strong Fe-K emission line with an equivalent width of &gt; 700 eV is found in 26 objects. Six of. them are classified as Compton-thick AGNs, and four are represented by either Compton-thin or Compton-thick spectral models. The success rate of finding obscured AGNs combining our analysis and the literature is 92% if the 18 mu m condition is used. Of. the 26 objects, 4 are optically classified as an H II nucleus and are new "elusive AGNs" in which star formation activity likely overwhelms AGN emission in the optical and infrared bands.

DOI： 10.1088/0004-637X/814/1/11

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DOI： 10.1117/1.JATIS.1.3.039801

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

DOI： 10.11316/jpsgaiyo.70.2.0_346

CiNii Books

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Publishing type：Research paper (scientific journal)  

© The Authors. We study a lightweight x-ray mirror with a carbon fiber reinforced plastic (CFRP) substrate for next-generation x-ray satellites. For tightly nested x-ray mirrors, such as those on the Suzaku and ASTRO-H telescopes, CFRP is the suitable substrate material because it has a higher strength-to-weight ratio and forming flexibility than those of metals. In flat CFRP substrate fabrication, the surface waviness has a root mean square (RMS) of ∼1 μm in the best products. The RMS approximately reaches a value consistent with the RMS of the mold used for the forming. We study the effect of moisture absorption using accelerated aging tests in three environments. The diffusivity of the CFRP substrate at 60°C and at relative humidity of 100% is ∼9.7×10-4 mm2·h-1, and the acceleration rate to the laboratory environment was 180 times higher. We also develop co-curing functional sheets with low water-vapor transmissivity on the CFRP substrate. Co-curing the sheets successfully reduced the moisture absorption rate by 440 times compared to the un-co-cured substrate. Details of the CFRP substrate fabrication and moisture absorption tests are also reported.

DOI： 10.1117/1.JATIS.1.3.034003

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© 2014 Optical Society of America. The new Japanese x-ray astronomy satellite, ASTRO-H, will carry two identical hard x-ray telescopes (HXTs), which cover the energy range of 5 to 80 keV. The HXT mirrors employ tightly nested, conically approximated thin-foil Wolter-I optics, and the mirror surfaces are coated with Pt/C depth-graded multilayers to enhance the hard x-ray effective area by means of Bragg reflection. The HXT comprises foils 120-450 mm in diameter and 200 mm in length, with a focal length of 12 m. To obtain a large effective area, 213 aluminum foils 0.2 mm in thickness are tightly nested confocally. The requirements for HXT are a total effective area of >300 cm2 at 30 keV and an angular resolution of <1.70 in halfpower diameter (HPD). Fabrication of two HXTs has been completed, and the x-ray performance of each HXT was measured at a synchrotron radiation facility, SPring-8 BL20B2 in Japan. Angular resolutions (HPD) of 1.9′ and 1.8′ at 30 keV were obtained for the full telescopes of HXT-1 and HXT-2, respectively. The total effective area of the two HXTs at 30 keV is 349 cm2.

DOI： 10.1364/AO.53.007664

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PubMed

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP SCIENCES S A  

The narrow component of the iron K alpha is an almost ubiquitous feature in the X-ray spectra of active galactic nuclei (AGN) and is believed to originate in neutral material, possibly located in the molecular torus. This would imply a tight connection between the Fe K alpha equivalent width (EW) and the physical properties of the torus. In a recent work we have shown that the decrease in the covering factor of the torus with the luminosity, as expected by luminosity-dependent unification models, would be able to explain the decrease in be K alpha EW with the luminosity (i.e. the X-ray Baldwin effect). Recent developments in the study of the mid-IR (MIR) spectrum of AGN allow important parameters of the torus to be deduced, such as its covering factor (f(obs)) and equatorial column density (N-H(T)). by applying clumpy torus models. Using XMM-Newton/EPIC observations of a sample of 24 type-I AGN, we investigate the relation between the physical parameters of the torus obtained by recent MIR works and the properties of the Fe K alpha line. We correct the values of the Fe K alpha LW by taking the inclination angle, the photon index, the equatorial column density, and half opening angle of the torus into account using a physical torus model of X-ray reprocessed radiation. We find that the relation between be K alpha LW and f(obs) shows a slope that is consistent with the expected value, albeit with low statistical significance. A trend that is consistent with the theoretical prediction is also found when comparing the Fe K alpha LW to N. Our work seems to confirm that the bulk of the narrow Fe K alpha line is produced by the same material responsible for the MIR emission.

DOI： 10.1051/0004-6361/201322701

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The narrow Fe K alpha line is one of the main signatures of the reprocessing of X-ray radiation from the material surrounding supermassive black holes, and it has been found to be omnipresent in the X-ray spectra of active galactic nuclei (AGN). In this work, we study the characteristics of the narrow Fe K alpha line in different types of AGN. Using the results of a large Suzaku study, we find that Seyfert 2s have on average lower Fe K alpha luminosities than Seyfert 1s for the same 10-50 keV continuum luminosity. Simulating dummy Seyfert 1s and Seyfert 2s populations using physical torus models of X-ray reflected emission, we find that this difference can be explained by means of different average inclination angles with respect to the torus, as predicted by the unified model. Alternative explanations include differences in the intensities of Compton humps, in the photon index distributions or in the average iron abundances. We show that the ratio between the flux of the broad and narrow Fe K alpha line in the 6.35-6.45 keV range depends on the torus geometry considered, and is on average &lt; 25 per cent and &lt; 15 per cent for type-I and type-II AGN, respectively. We find evidence of absorption of the narrow Fe K alpha line flux in Compton-thick AGN, which suggests that part of the reflecting material is obscured. We estimate that on average in obscured AGN the reflected radiation from neutral material is seen through a column density which is 1/4 of that absorbing the primary X-ray emission. This should be taken into account in synthesis models of the CXB and when studying the luminosity function of heavily obscured AGN. We detect the first evidence of the X-ray Baldwin effect in Seyfert 2s, with the same slope as that found for Seyfert 1s, which suggests that the mechanism responsible for the decrease of the equivalent width with the continuum luminosity is the same in the two classes of objects.

DOI： 10.1093/mnras/stu735

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The X-ray Baldwin effect is the inverse correlation between the equivalent width (EW) of the narrow component of the iron K alpha line and the X-ray luminosity of active galactic nuclei (AGN). A similar trend has also been observed between Fe K alpha EW and the Eddington ratio (lambda(Edd)). Using Chandra/High Energy Grating results of Shu et al. and bolometric corrections we study the relation between EW and lambda(Edd), and find that log EW = ( - 0.13 +/- 0.03)log lambda(Edd) + 1.47. We explore the role of the known positive correlation between the photon index of the primary X-ray continuum Gamma and lambda(Edd) on the X-ray Baldwin effect. We simulate the iron K alpha line emitted by populations of unabsorbed AGN considering three different geometries of the reflecting material: toroidal, spherical-toroidal and slab. We find that the Gamma-lambda(Edd) correlation cannot account for the whole X-ray Baldwin effect, unless a strong dependence of Gamma on lambda(Edd), such as the one recently found by Risaliti et al. and Jin et al., is assumed. No clear correlation is found between EW and Gamma. We conclude that a good understanding of the slope of the Gamma-lambda(Edd) relation is critical to assess whether the trend plays a leading or rather a marginal role in the X-ray Baldwin effect.

DOI： 10.1093/mnras/stt1326

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Language：English   Publishing type：Research paper (international conference proceedings)  

We report a first result from a ground-based X-ray calibration of the ASTRO-H Hard X-ray Telescope (HXT) at a synchrotron radiation facility SPring-8. ASTRO-H, to be launched in 2015, is Japan's sixth X-ray satellite mission following to Suzaku satellite. One of the features of ASTRO-H is a simultaneous observation between 0.3 keV to 600 keV with several instruments. ASTRO-H will carry two HXTs to cover hard x-rays up to 80 keV. HXT, which is one of the key instruments in ASTRO-H, is the conically approximated Wolter-I grazing incidence optics similar to the Suzaku X-ray telescope. Reflector surfaces are coated with depth-graded Platinum and Carbon multilayer to reflect hard X-rays efficiently. The integrations of the flight optics of HXT-1 and HXT- 2 were completed, and we performed a ground calibration of HXT-1 at a synchrotron facility, SPring-8 beamline BL20B2 to build a response function of HXT. We use a raster scan method with a pencil beam at the baseline length of 215m. A point spread function and effective area were measured at 30, 40, 50, 60, 70keV. From a preliminary analysis of the data, an angular resolution of 1.5 - 1.9 arcmin. was obtained at five energy band in the full telescope. The effective area is 170 cm2 at 30 keV and 82 cm2 at 50 keV, respectively. The effective area at 30 and 50 keV are about 13 % and 50 % larger than expected, respectively. We also measured the stray light from outside of field of view at 12' and 20' of-axis angle. We confirmed the effectiveness of pre-collimator to reduce the stray lights. © 2013 SPIE.

DOI： 10.1117/12.2024764

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP SCIENCES S A  

The existence of an anti-correlation between the equivalent width (EW) of the narrow core of the iron Ka line and the luminosity of the continuum (i.e., the X-ray Baldwin effect) in type I active galactic nuclei has been confirmed in recent years by several studies carried out with XMM-Newton, Chandra and Suzaku. However, no general consensus on the origin of this trend has been reached so far. Several works have proposed the decrease of the covering factor of the molecular torus with the luminosity (in the framework of the luminosity-dependent unification models) as a possible explanation for the X-ray Baldwin effect. Using the fraction of obscured sources measured by recent X-ray and infrared (IR) surveys as a proxy of the half-opening angle of the torus and recent Monte Carlo simulations of the X-ray radiation reprocessed by a structure with a spherical-toroidal geometry, we test the hypothesis that the X-ray Baldwin effect is related to the decrease of the half-opening angle of the torus with the luminosity. Simulating the spectra of an unabsorbed population with a luminosity-dependent covering factor of the torus as predicted by recent X-ray surveys, we find that this mechanism is able to explain the observed X-ray Baldwin effect. Fitting the simulated data with a log-linear L2-10keV-EW relation, we found that in the Seyfert regime (L2-10keV &lt;= 10(44.2) erg s(-1)) luminosity-dependent unification produces a slope consistent with the observations for average values of the equatorial column densities of the torus of log N-H(T) greater than or similar to 23.1, and can reproduce both the slope and the intercept for log N-H(T) similar or equal to 23.2. Lower values of N-H(T) are obtained assuming the decrease of the covering factor of the torus with the luminosity extrapolated from IR observations (22.9 less than or similar to log N-H(T) less than or similar to 23). In the quasar regime (L2-10keV &gt; 10(44.2) erg s(-1)), a decrease of the covering factor of the torus with the luminosity slower than that observed in the Seyfert regime (as found by recent hard X-ray surveys) is able to reproduce the observations for 23.2 less than or similar to log N-H(T) less than or similar to 24.2.

DOI： 10.1051/0004-6361/201220324

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We report the discovery of a candidate active galactic nucleus (AGN), 2XMM J123103.2+110648 at z = 0.13, with an X-ray spectrum represented purely by soft thermal emission reminiscent of Galactic black hole (BH) binaries in the disk-dominated state. This object was found in the second XMM-Newton serendipitous source catalog as a highly variable X-ray source. In three separate observations, its X-ray spectrum can be represented either by a multicolor disk blackbody model with an inner temperature of kT(in) approximate to 0.16-0.21 keV or a Wien spectrum Comptonized by an optically thick plasma with kT approximate to 0.14-0.18 keV. The soft X-ray luminosity in the 0.5-2 keV band is estimated to be (1.6-3.8) x 10(42) erg s(-1). Hard emission above similar to 2 keV is not detected. The ratio of the soft to hard emission is the strongest among AGNs observed thus far. Spectra selected in high/low-flux time intervals are examined in order to study spectral variability. In the second observation with the highest signal-to-noise ratio, the low-energy (below 0.7 keV) spectral regime flattens when the flux is high, while the shape of the high-energy part (1-1.7 keV) remains unchanged. This behavior is qualitatively consistent with being caused by strong Comptonization. Both the strong soft excess and spectral change consistent with Comptonization in the X-ray spectrum imply that the Eddington ratio is large, which requires a small BH mass (smaller than similar to 10(5) M-circle dot).

DOI： 10.1088/0004-637X/752/2/154

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present the results of X-ray variability and spectral analysis of a sample of 15 new candidates for active galactic nuclei with relatively low-mass black holes (BHs). They are selected from the Second XMM-Newton Serendipitous Source Catalogue based on strong variability quantified by normalized excess variances. Their BH masses are estimated to be (1.1-6.6) x 10(6) M-circle dot by using a correlation between excess variance and BH mass. Seven sources have estimated BH masses smaller than 2 x 10(6) M-circle dot, which are in the range for intermediate-mass black holes. Eddington ratios of sources with known redshifts range from 0.07 to 0.46 and the mean Eddington ratio is 0.24. These results imply that some of our sources are growing supermassive black holes, which are expected to have relatively low masses with high Eddington ratios. X-ray photon indices of the 15 sources are in the range of approximate to 0.57-2.57 and 5 among them have steep (&gt;2) photon indices, which are the range for narrow-line Seyfert 1s. Soft X-ray excess is seen in 12 sources and is expressed by a blackbody model with kT approximate to 83-294 eV. We derive a correlation between X-ray photon indices and Eddington ratios, and find that the X-ray photon indices of about a half of our sources are flatter than the positive correlation suggested previously.

DOI： 10.1088/0004-637X/751/1/39

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Language：English   Publishing type：Research paper (international conference proceedings)  

Japan's sixth X-ray satellite mission ASTRO-H is planned to be launched in 2014. Hard X-ray Telescope (HXT) to cover hard X-rays up to 80 keV is thin-foil, multi-nested conical optics with depth-graded Pt/C multilayer. The mass production of the reflectors for the flight model has been going on since August 2010. We have introduced a new screening method for replication mandrels with optical imagers. In addition, we have adopted a new replication mandrel which consists of glass tube coated with thin glass sheet for large size mandrels. The selected 212 pairs (95 pairs (segment 1), 59 pairs (segment 2), 58 pairs (segment 3)) of multilayer mirror have been characterized at a large synchrotron radiation facility, Spring-8 beamline BL20B2. We present the current status of reflector production and hard X-ray characterization for HXT. © 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

DOI： 10.1117/12.893155

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

The broadband spectra of two Swift/BAT active galactic nuclei (AGNs) obtained from Suzaku follow-up observations are studied: NGC 612 and NGC 3081. Fitting with standard models, we find that both sources show similar spectra characterized by heavy absorption with N-H similar or equal to 10(24) cm(-2), and the fraction of scattered light is f(scat) = 0.5%-0.8%, and the solid angle of the reflection component is Omega/2 pi = 0.4-1.1. To investigate the geometry of the torus, we apply numerical spectral models utilizing Monte Carlo simulations by Ikeda et al. to the Suzaku spectra. We find that our data are well explained by this torus model, which has four geometrical parameters. The fit results suggest that NGC 612 has a torus half-opening angle of similar or equal to 60 degrees-70 degrees. and is observed from a nearly edge-on angle with a small amount of scattering gas, while NGC 3081 has a very small opening angle of similar or equal to 15 degrees and is observed on a face-on geometry, more like the deeply buried "new type" AGNs found by Ueda et al. We demonstrate the potential power of direct application of such numerical simulations to high-quality broadband spectra to unveil the inner structure of AGNs.

DOI： 10.1088/0004-637X/729/1/31

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

ASTRO-H is a general purpose X-ray observatory scheduled for launch in 2014. Two soft X-ray telescopes (SXT) and two hard X-ray telescopes (HXT) will be onboard covering energy range of 0.2 -80 keV. Thermal control of the telescope is similar to that of Suzaku, using a thermal shield (TS) placed in front of the telescope and a electric heater attached on the telescope housing. Thus it is required for a TS to have high soft X-ray transmission, low solar absorptance and a low infrared emissivity. To meet these requirement, TS should be made of thin plastic film coated by metal such as aluminum. Then most important property of TS is mechanical strength to survive various environments at the launch and in orbit. This paper describes designing of TS, method of TS production, various environmental conditions and tests, risk management of treatment of ultra-thin film of TS in the process of production, testing and assembling.

DOI： 10.1117/12.893368

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We present the current status of hard X-ray telescope developments of ASTRO-H. ASTRO-H is Japan's 6th Xray satellite mission following to Suzaku. It will be launched in 2014. The HXT onboard ASTRO-H is thin-foil, multi-nested conical optics as well as Suzaku XRT. To reflect hard X-rays efficiently, reflector surfaces are coated with depth-graded Pt/C multilayer. Reflectors are fabricated by the epoxy-replication method. Currently, we have finished the preparation of mirror production facility at Nagoya University, and started test production of reflectors for HXT. The selected 22 pairs of multilayer reflectors have been characterized at the SPring-8 beamline BL20B2.

DOI： 10.1117/12.857421

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present results from the Suzaku observation of the microquasar GRS 1915+105 performed during the 2005 October multiwavelength campaign. The data include both stable state (class chi) and limit-cycle oscillation (class theta). Correct interstellar absorption as well as effects of dust scattering are fully taken into account in the spectral analysis. The energy spectra in the 2-120 keV band in both states are all dominated by strong Comptonization of disk photons by optically thick (tau approximate to 7-10) and low-temperature (T-e approximate to 2-3 keV) hybrid plasmas containing non-thermal electrons produced with 10%-60% of the total power input. Absorption lines of highly ionized Fe ions detected during the oscillation indicate that a strong disk wind is developed. The ionization stage of the wind correlates with the X-ray flux, supporting the photoionization origin. The iron-K emission line shows a strong variability during the oscillation; the reflection is strongest during the dip but disappears during the flare. We interpret this as evidence for "self-shielding" that the Comptonizing corona becomes geometrically thick in the flare phase, preventing photons from irradiating the outer disk. The low-temperature and high-luminosity disk emission suggests that the disk structure is similar to that in the very high state of canonical black hole binaries. The spectral variability during the oscillation is explained by the change of the disk geometry and of the physical parameters of Comptonizing corona, particularly the fractional power supplied to the acceleration of non-thermal particles.

DOI： 10.1088/0004-637X/713/1/257

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We construct a new sample of 32 obscured active galactic nuclei (AGNs) selected from the Second XMM-Newton Serendipitous Source Catalogue to investigate their multiwavelength properties in relation to the "scattering fraction," the ratio of the soft X-ray flux to the absorption-corrected direct emission. The sample covers a broad range of the scattering fraction (similar to 0.1%-10%). A quarter of the 32 AGNs have a very low scattering fraction (&lt;= 0.5%), which suggests that they are buried in a geometrically thick torus with a very small opening angle. We investigate correlations between the scattering fraction and multiwavelength properties. We find that AGNs with a small scattering fraction tend to have low [OIII]lambda 5007/X-ray luminosity ratios. This result agrees with the expectation that the extent of the narrow-line region is small because of the small opening angle of the torus. There is no significant correlation between scattering fraction and far-infrared luminosity. This implies that a scale height of the torus is not primarily determined by starburst activity. We also compare scattering fraction with black hole mass or Eddington ratio and find a weak anti-correlation between the Eddington ratio and scattering fraction. This implies that more rapidly growing supermassive black holes tend to have thicker tori.

DOI： 10.1088/0004-637X/711/1/144

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Japan's 6th X-ray satellite mission ASTRO-H, which is planed to be launched in the fiscal year 2013, will carry two hard X-ray telescopes (HXT) using depth-graded multilayer reflectors which provide us the capability of hard X-ray imaging observation up to 80 keV. ASTRO-H/HXT is the light-weight hard X-ray telescope using Pt/C depth-graded multilayer and high-through put thin-foil optics. The basic technology for fabricating ASTRO-H/HXT has been established through the balloon borne experiments, InFOC mu S and SUMIT mission. The HXT consists of about 1300 foil reflectors of which a size of the 200 mm mirror length and the diameter range of 120-450 mm which is much larger that those for the balloon borne experiments. To clear the requirements of the angular resolution and the effective photon collecting are a for ASTRO-H/HXT, we should produce twice the total number of reflectors and select them. Therefore we need to produce more than 5000 foil reflectors for the two flight telescopes. The installation of the production line and optical evaluation system dedicated to the ASTRO-H/HXT has been almost done. We are testing and improving the production line through productions of several sizes of reflectors. The mass production of the reflectors for the flight model is scheduled to start from July 2010.

DOI： 10.1117/12.856827

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

We present results from observations of three type 2 quasar candidates with Suzaku and XMM-Newton. These are type 2 ULIRGs with quasar classification selected from the IRAS 1 Jy sample. We analyze their X-ray spectra to investigate the AGN power in these ULIRGs. The X-ray spectra are explained by a combination of unabsorbed and absorbed power-law components with Gamma = 1.48-2.40. The best-fit N-H for the absorbed component is in the range of (9.1-76) x 10(22) cm(-2). The absorption-corrected L2-10keV of AGNs are in the range for Seyferts ((4.3-24) x 10(42) erg s(-1)).

DOI： 10.1063/1.3475291

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Publishing type：Research paper (international conference proceedings)  

© 2010 SPIE. The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the high-energy universe by performing high-resolution, high-throughput spectroscopy with moderate angular resolution. ASTRO-H covers very wide energy range from 0.3 keV to 600 keV. ASTRO-H allows a combination of wide band X-ray spectroscopy (5-80 keV) provided by multilayer coating, focusing hard X-ray mirrors and hard X-ray imaging detectors, and high energy-resolution soft X-ray spectroscopy (0.3-12 keV) provided by thin-foil X-ray optics and a micro-calorimeter array. The mission will also carry an X-ray CCD camera as a focal plane detector for a soft X-ray telescope (0.4-12 keV) and a non-focusing soft gamma-ray detector (40-600 keV). The micro-calorimeter system is developed by an international collaboration led by ISAS/JAXA and NASA. The simultaneous broad bandpass, coupled with high spectral resolution of ΔE ~7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be pursued.

DOI： 10.1117/12.857875

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

We present a new sample of 38 obscured AGNs selected from the Second XMM-Newton Serendipitous Source Catalogue. This sample covers a wide range of scattering fractions, which are ratios of soft X-rays to direct emission from the nucleus and reflect opening angle of the obscuring torus. We find strong candidates for buried AGNs in the sample and multiwavelength properties for the sample are summarized.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present the results of X-ray spectral analysis of 22 active galactic nuclei (AGNs) with a small scattering fraction selected from the Second XMM-Newton Serendipitous Source Catalogue using hardness ratios. They are candidates of buried AGNs, since a scattering fraction, which is a fraction of scattered emission by the circumnuclear photoionized gas with respect to direct emission, can be used to estimate the size of the opening part of an obscuring torus. Their X-ray spectra are modeled by a combination of a power law with a photon index of 1.5-2 absorbed by a column density of similar to 10(23-24) cm(-2), an unabsorbed power law, narrow Gaussian lines, and some additional soft components. We find that scattering fractions of 20 among 22 objects are less than a typical value (similar to 3%) for Seyfert 2s observed so far. In particular, those of eight objects are smaller than 0.5%, which are in the range for buried AGNs found in recent hard X-ray surveys. Moreover, [O III]lambda 5007 luminosities at given X-ray luminosities for some objects are smaller than those for Seyfert 2s previously known. This fact could be interpreted as a smaller size of optical narrow emission-line regions produced in the opening direction of the obscuring torus. These results indicate that they are strong candidates for the AGN buried in a very geometrically thick torus.

DOI： 10.1088/0004-637X/705/1/454

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP SCIENCES S A  

Context. In recent years, several Seyfert 2 galaxies have been discovered that change state when observed in X-rays a few years apart, switching from Compton-thin to reflection-dominated or viceversa.
Aims. We observed a member of this class of "Changing-look" sources, the Phoenix galaxy, with Suzaku, with the aim of better understanding the nature of the variations.
Methods. The Suzaku spectrum was analyzed, and the results compared with previous ASCA and XMM-Newton observations.
Results. The source was caught in a Compton-thin state, as in XMM-Newton, but differently from ASCA. Comparing the Suzaku and XMM-Newton observations, a variation in the column density of the absorber on a time scale of years is discovered. A similar change, but on much shorter time scales (i.e. ks) may also explain the count-rate variations during the Suzaku observations. A soft excess is also present, likely due to continuum and line emission from photoionized circumnuclear matter.

DOI： 10.1051/0004-6361/200811049

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Monte Carlo simulation is one of the best tools to study the complex spectra of Compton-thick active galactic nuclei (AGNs) and to figure out the relation between their nuclear structures and X-ray spectra. We have simulated X-ray spectra of Compton-thick AGNs obscured by an accretion torus whose structure is characterized by a half-opening angle, an inclination angle of the torus relative to the observer, and a column density along the equatorial plane. We divided the simulated spectra into three components: one direct component, an absorbed reflection component, and an unabsorbed reflection component. We then deduced the dependences of these components on the parameters describing the structure of the torus. Our simulation results were applied to fit the wide-band spectrum of the Seyfert 2 galaxy Mrk 3 obtained by Suzaku. The spectral analysis indicates that we observe the nucleus along a line of sight intercepting the torus near its edge, and the column density along the equatorial plane was estimated to be similar to 10(24) cm(-2). Using this model, we can estimate the luminosities of both the direct emission and the emission irradiating the surrounding matter. This is useful to find the time variability and time lag between the direct and reflected light.

DOI： 10.1088/0004-637X/692/1/608

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We have obtained a broad-band spectrum of the Compton-thick Seyfert 2 galaxy NGC 2273 with Suzaku. The spectrum reveals the first detection of hard X-rays above similar to 10 keV from NGC 2273. The broad-band spectrum is well represented by a three component model, accompanied by both a strong iron K alpha line with an equivalent width of similar to 1.8 keV and several weak lines. The three component model consists of a soft component, a reflection component from cold matter, and an absorbed power law component. The soft component can be represented by thin thermal emission with kT similar to 0.56 keV or by a scattered component with a scattering fraction of 0.4%. Fixing the photon indices of the power law and reflection components at 1.9, we found that the power law component, heavily absorbed by gas with a column density of similar to 1.5 x 10(24) cm(-2), has an intrinsic 2-10 keV luminosity of similar to 1.7 x 10(42) erg s(-1). We also applied a reflection model based on a Monte Carlo simulation, assuming a simple torus geometry. We found that the model fits the broad band spectrum well, and we placed some tentative constraints on the geometry of the putative torus in NGC 2273.

DOI： 10.1093/pasj/61.sp1.S317

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We present the current state of the development system of the hard ray telescope onboard ASTRO-H satellite.
Japan's 6th X-ray satellite mission ASTRO-H, which is planed to be launched in fiscal year 2013, will carry four X-ray telescopes (XRT). Two of four XRTs are hard X-ray telescopes (HXT) using depth-graded multilayer reflector which provide us the capability of hard X-ray imaging observation up to 80 keV. ASTRO-H/HXT is the light-weight hard X-ray telescope using Pt/C depth-graded multilayer and high-throughput thin-foil optics. The basic technology for fabricating the ASTRO-H/HXT has been established through the balloon borne experiments, "InFOC mu S" (US-Japan international joint experiment) and "SUMIT" missions. (Nagoya University, Osaka University and JAXA). Major changes from XRTs onboard InFOC mu S and SUMIT missions are large aperture size of 45 cm in diameter, the length of reflectors of 20 cm and the focal length of 12 m (XRTs onboard the balloon missions above have the aperture size of 40 cm in diameter, 13 cm long reflectors and 8 m focal length). Now we have almost finished to establish the mirror production facility dedicated to the ASTRO-H/HXT and are starting to produce foil reflectors for performance verification of 200 mm long reflector. We report the current status of the development facilities and test foil production

DOI： 10.1117/12.825771

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ASTRONOMICAL SOC PACIFIC  

We present a new sample of AGNs buried in a torus with a very small opening angle selected from the XMM-Newton serendipitous source catalogue using hardness ratios. In 8/22 objects, the fraction of scattered X-ray emission from the opening part of the torus with respect to the direct emission is less than 0.5%, which is much smaller than a typical value (3%) for Seyfert 2s. Moreover, [OIII] lambda 5007 luminosities for our sample are smaller than those for other Seyfert 2s at a given X-ray luminosity. These results suggest that they are strong candidates of AGN buried in a very geometrically-thick torus.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We report on a Suzaku observation of the nearby Seyfert 2 galaxy NGC 4388. The overall spectrum is well described by the combination of strongly absorbed power-law plus thin thermal plasma emission, as well as previous observations. Thanks to well-calibrated instruments and a low background level, Suzaku measured the broad-band X-ray spectra more precisely than ever, and enabled us to probe the physical structure of the nuclear region. In addition, a time variability having a factor of 1.5 with a half-day time scale was found up to above 10keV. The center energy and the K beta/K alpha ratio of the narrow Fe-K line, together with less time variability, indicate that the fluorescent material is far from the black hole. A spectral hump around the 30-40 keV band, together with a Compton shoulder of the Fe-K line, requires a significant contribution of the reflection component. This is also consistent with a smaller amplitude of time variability in a higher energy band. A large contribution of the reflection component was not observed by the CGRO/OSSE and BeppoSAX, suggesting that NGC 4388 had been in a higher flux state, and that Suzaku observed its light echo. A He-like Fe-Ku absorption line was also detected, indicating the existence of highly ionized plasma.

DOI： 10.1093/pasj/60.sp1.S263

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We obtained a wide-band spectrum of the Compton-thick Seyfert 2 galaxy Mkn 3 with Suzaku. The observed spectrum was clearly resolved into weak, soft power-law emission, a heavily absorbed power-law component, cold reflection, and many emission lines. The heavily absorbed component, absorbed by gas with a column density of 1. 1 x 10(24) cm(-2), has an intrinsic 2-10 keV luminosity of similar to 1. 6 x 10(43) erg s(-1), and is considered to be direct emission from the Mkn 3 nucleus. The reflection component was interpreted as being the reflection of direct light off a cold, thick material; the reflection fraction, R, was 1.36 +/- 0.20. The cold material is inferred to be located &gt; 1 pc from the central black hole of Mkn 3, due to the low ionization parameter of iron ( xi I erg cm s(-1)) and the narrow iron line width (sigma &lt; 22 eV). The weak, soft power-law emission is considered to be scattered light by ionized gas with a scattering fraction of 0.9 +/- 0.2%. The existence of many highly ionized lines in the observed spectrum indicates that the ionized gas has a broad ionized structure, with xi = 10-1000 erg cm s(-1). This high-quality spectrum obtained by Suzaku can be considered to be a template for studies of Seyfert 2 galaxies.

DOI： 10.1093/pasj/60.sp1.S293

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We present results from a 150 ks Suzaku observation of the Seyfert 1.5 NGC 3516 in 2005 October. The source was in a relatively highly absorbed state. Our best-fit model is consistent with the presence of a low-ionization absorber having a column density near 5 X 1022 cm(-2) and covering most of the X-ray continuum source (covering fraction 96-100%). A high-ionization absorbing component, which yields a narrow absorption feature consistent with Fe xxvi K, is confirmed. A relativistically broadened Fe K alpha line was required in all fits, even after the complex absorption was taken into account; an additional partial-covering component is an inadequate substitute for the continuum curvature associated with the broad Fe line. A narrow Fe Ka emission line has a velocity width consistent with the Broad Line Region. The low-ionization absorber may be responsible for producing the narrow Fe Ka line, though a contribution from additional material out of the line of sight is possible. We include in our model soft band emission lines from He- and H-like ions of N, O, Ne, and Mg, consistent with photo-ionization, though a small contribution from collisionally-ionized emission is possible.

DOI： 10.1093/pasj/60.sp1.S277

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The compact group of galaxies HCG 62 (z = 0.0145) was observed for 120 ks with Suzaku XIS and HXD-PIN. The XIS spectra for four annular regions were fitted with a two-temperature vapec model with variable abundance, combined with the foreground Galactic component. The Galactic component was described by a two-temperature apec model, and constrained to have a common surface brightness among the four annuli. We confirmed the multitemperature nature of the intra-group medium, as reported previously, with a doughnut-like high temperature ring at radii 3'3-6'5. Abundances of Mg, Si, S, and Fe were well-constrained. We examined the possible "high-abundance arc" at'- 2; southwest from the center; however, Suzaku data did not confirm it. We suspect that it is a misidentification of an excess hot component in this region as the Fe line. Neither XIS (5-12 keV) nor HXD-PIN (12-40 keV) gave positive detection of the extended hard X-rays previously reported with ASCA, although our upper limit did not exclude the ASCA result. The 5-12 keV intensity in the r < 33 region turned out to be 70 19% higher than the nominal CXB level, and Chandra and Suzaku data suggest a concentration of hard X-ray sources with an average photon index of F = 1.3 8 0.06. The cumulative mass of 0, Fe, and Mg in the intra-group medium and the metal mass-to-light ratio were compared with those in other groups. The possible role of AGN or galaxy mergers in this group is also discussed.

DOI： 10.1093/pasj/60.sp1.S317

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

Suzaku observed a nearby Seyfert 2 galaxy, NGC 4945, which hosts one of the brightest active galactic nuclei above 20keV. Combining data from the two detectors aboard Suzaku, the AGN intrinsic nuclear emission and its reprocessed signals were observed simultaneously. The intrinsic emission is highly obscured with an absorbing column of similar to 5 X 10(24) CM-2. The spectrum below 10 keV is dominated by a reflection continuum and emission lines from neutral/ionized material. Along with a neutral iron K alpha line, a neutral iron K alpha line and a neutral nickel Ka line were detected for the first time from this source. The neutral lines and the cold reflection continuum are consistent with both originating in the same location. The Compton down-scattered shoulder in the neutral Fe-K alpha line is similar to 10% in flux of the narrow core, which confirms that the line originates from reflection, rather than transmission. The flux of the intrinsic emission varied by a factor of similar to 2 within similar to 20 ks, which requires the obscuring material to be geometrically thin. Broadband spectral modeling showed that the solid angle of the neutral reflector is less than a few x 10(-2) x 2 pi. All of this evidence regarding the reprocessed signals suggests that a disk-like absorber/reflector is viewed from a near edge-on angle.

DOI： 10.1093/pasj/60.sp1.S251

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Publishing type：Research paper (international conference proceedings)  

We report in-flight status of the X-ray detectors on board the Suzaku observatory, the 5th X-ray astronomy satellite of Japan launched on July 10, 2005. Suzaku is equipped with two types of Instruments: one is the X-ray Imaging Spectrometers (XISs) and the other is Hard X-ray Detector (HXD). XIS utilizes the X-ray CCD camera in combination with the grazing-incidence X-ray telescope. HXD is a non-imaging, hybrid detector utilizing Si PIN diodes and GSO/BGO phoswich counters. Suzaku takes a low-earth, circular orbit with an altitude of 560 km and an inclination of 31 deg. This means that Suzaku goes through the south atlantic anomaly about 1/3 of its revolutions. This has a large impact on the in-flight performance of XIS and HXD, which is reported in detail in the present paper. © 2007 IEEE.

DOI： 10.1109/NSSMIC.2007.4436667

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：Institute of Physics Publishing  

A Suzaku observation of the nucleus of the radio-loud AGN Centaurus A in 2005 has yielded a broadband spectrum spanning 0.3-250 keV. The net exposure times after screening were 70 ks per X-ray Imaging Spectrometer (XIS) camera, 60.8 ks for the Hard X-ray Detector ( HXD) PIN, and 17.1 ks for the HXD GSO. The hard X-rays are fit by two power laws of the same slope, absorbed by columns of 1.5 and 7 × 1023 cm-2, respectively. The spectrum is consistent with previous suggestions that the power-law components are X-ray emission from the subparsec VLBI jet and from Bondi accretion at the core, but it is also consistent with a partial-covering interpretation. The soft band is dominated by thermal emission from the diffuse plasma and is fit well by a two-temperature VAPEC model, plus a third power-law component to account for scattered nuclear emission, jet emission, and emission from X-ray binaries and other point sources. Narrow fluorescent emission lines from Fe, Si, S, Ar, Ca, and Ni are detected. The Fe Ka line width yields a 200 It-day lower limit on the distance from the black hole to the line-emitting gas. Fe, Ca, and S K-shell absorption edges are detected. Elemental abundances are constrained via absorption edge depths and strengths of the fluorescent and diffuse plasma emission lines. The high metallicity ([Fe/H] = +0.1) of the circumnuclear material suggests that it could not have originated in the relatively metal-poor outer halo unless enrichment by local star formation has occurred. Relative abundances are consistent with enrichment from Type II and Ia supernovae. 2007. The American Astronomical Society. All rights reserved.

DOI： 10.1086/519271

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We analyzed discrete sources in a typical starburst galaxy, NGC 1808, with Chandra in order to study the relation between X-ray and star-forming activities. We detected thirty-eight X-ray sources with an X-ray luminosity (Lx) of &gt; 10(37) erg s(-1) in the central 5'x5' (13.4 kpc x 13.4 kpc) region. About 90% of the hard X-rays previously detected with ASCA came from these discrete sources. Among the detected sources, sixteen sources had an L-X of &gt; 10(38) erg s(-1). The number of luminous sources is nearly equal to that of M 82, although their concentration into the central star-forming region is lower than that of M 82. There are several soft X-ray sources with a temperature of 0.6 keV in the central star-forming region. The X-ray properties of the soft sources are similar to those of a H II region, or a supernova remnant. The existence of both luminous sources and soft X-ray sources indicates the star-forming activity of NGC 1808. However, we detected only a few candidates of high-mass X-ray binaries that would be produced by enhanced star-forming activity. This may be due to the starburst age of NGC 1808.

DOI： 10.1093/pasj/59.3.531

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The XIS is an X-ray Imaging Spectrometer system, consisting of state-of-the-art charge-coupled devices (CCDs) optimized for X-ray detection, camera bodies, and control electronics. Four sets of XIS sensors are placed at the focal planes of the grazing-incidence, nested thin-foil mirrors (XRT: X-Ray Telescope) orboard the Suzaku satellite. Three of the XIS sensors have front-illuminated CCDs, while the other has a back-illuminated CCD. Coupled with the XRT, the energy range of 0.2-12 keV with energy resolution of 130 eV at 5.9 keV, and a field of view of 18' x 18' are realized. Since the Suzaku launch on 2005 July 10, the XIS has been functioning well.

DOI： 10.1093/pasj/59.sp1.S23

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

High-sensitivity wide-band X-ray spectroscopy is the key feature of the Suzaku X-ray observatory, launched on 2005 July 10. This paper summarizes the spacecraft, in-orbit performance, operations, and data processing that are related to observations. The scientific instruments, the high-throughput X-ray telescopes, X-ray CCD cameras, non-imaging hard X-ray detector are also described.

DOI： 10.1093/pasj/59.sp1.S1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The extended X-ray emission from 'the Cap' region, located 11' (11.6 kpc) above the disk of the starburst galaxy M 82, has been observed with Suzaku and XMM-Newton. Owing to the good energy resolution and the large collecting area of the XIS on Suzaku, combined with similar properties of the EPIC instrument on XMM-Newton, we have clearly detected K-shell emission lines from O VII, O VIII, Ne X, Mg XI, Mg XII, Sr XIII, and the Fe L complex. Two optically thin thermal plasma components are required to fit the observed X-ray spectra. We have determined the metal abundances of O, Ne, Mg, Si, and Fe in this region for the first time. Their metal abundance ratios agree well with those of metal-poor stars and the model prediction of metals synthesized by type-II supernovae, but they are not consistent with the metallicities of type-la supernovae. This result is support for the idea that the origin of the metals in the Cap is type-II supernova explosions occurring in the starburst regions in the M 82 galaxy. We discuss the possible contribution from sputtered dust grains to the metals in the Cap. An emission line consistent with the C VI transition of n = 4 to 1 at 0.459 keV has been marginally detected, although it is not statistically significant at the 99% confidence level; the presence of this line would suggest charge-exchange processes in the Cap.

DOI： 10.1093/pasj/59.sp1.S269

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：IEEE  

We report in-flight status of the X-ray detectors on board the Suzaku observatory, the 5th X-ray astronomy satellite of Japan launched on July 10, 2005. Suzaku is equipped with two types of instruments: one is the X-ray Imaging Spectrometers (XISs) and the other is Hard X-ray Detector (HXD). XIS utilizes the X-ray CCD camera in combination with the grazing-incidence X-ray telescope. HXD is a non-imaging, hybrid detector utilizing Si PIN diodes and GSO/BGO phoswich counters. Suzaku takes a low-earth, circular orbit with an altitude of 560 km and an inclination of 31 deg. This means that Suzaku goes through the south atlantic anomaly about 1/3 of its revolutions. This has a large impact on the in-flight performance of XIS and HXD, which is reported in detail in the present paper.

DOI： 10.1109/NSSMIC.2007.4436667

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ASTRONOMICAL SOC PACIFIC  

Here we report the preliminary results on the Suzaku observations of the Seyfert 2 galaxy NGC 4388. The longest high-sensitibity wide-band Xray observation of this object for the first time revealed the time variability of spectra and the complex Fe-K line features.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We present the results of timing analysis of XMM-Newton observations of Seyfert 2 galaxies in order to search for differences in the mean properties of Seyfert 1 galaxies and Seyfert 2 galaxies. We selected 13 Seyfert 2 galaxies from the XMM-Newton archive that have hard X-ray components in their spectra and calculated the excess variance (sigma(2)(rms)) in the 2-10 keV band. We found that six Seyfert 2 galaxies (3C 98, IRAS 05189-2524, MCG - 5-23-16, NGC 6300, UGC 4203, and PKS 1814-637) have buried luminous nuclei and that the nuclei have timing properties similar to those of Seyfert 1 nuclei. This indicates that these galaxies are candidates for having buried Seyfert 1 nuclei as expected by the unified Seyfert model. The first five galaxies show significant time variability. The amplitude of the time variability of IRAS 05189-2524 is similar to that of narrow-line Seyfert 1 galaxies. In contrast, the amplitude of variability of the seven other galaxies is quite small, much smaller than that of Seyfert 1 galaxies with similar X-ray luminosity. The lack of short time variability in these objects is explained by the dominance of the reflection component in three galaxies (Mrk 3, Mrk 463, and NGC 7582), and by the presence of very massive black holes and an inferred low accretion rate in the other three galaxies (NGC 1052, NGC 4507, and NGC 7172). For Mrk 348, the significant time variability that is expected based on the estimate of the central black hole mass was not detected.

DOI： 10.1086/504405

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

We present preliminary results from a 150 ks Suzaku observation of the Seyfert 1 galaxy NGC 3516. Suzaku's wide bandpass has enabled us to deconvolve the broadband emitting and absorbing components in this object, breaking model degeneracies inherent in previous, smaller-bandpass spectra. The primary power-law continuum is absorbed by an ionized absorber as well as a partial-covering absorber; the column density of the ionized absorber has increased by a factor of similar to 3 since XMM-Newton observations in 2001. We detect a soft power-law component which may be scattered emission. We confirm the presence of the broad Fe line, finding a 185(-70)(+130) eV equivalent width line that indicates emission extending down to a few Schwarzschild radii. Models which exclude either the broad line or the partial-covering absorber are rejected. Suzaku's high effective area and low background near 6 keV also allow us to resolve the narrow Fe K emission line; we find a FWHM velocity width near 4000 km s(-1), commensurate with Broad Line Region velocities. (c) 2006 WILEY-VCH Verlag GmbH&Co. KGaA, Weinheim.

DOI： 10.1002/asna.200610697

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Language：English   Publishing type：Research paper (international conference proceedings)  

We give overview and the current status of the development of the Soft X-ray Imager (SXI) onboard the NeXT satellite. SXI is a back-illuminated supportless CCD (a combination of "back-illuminated CCD" and "supportless CCD") whose imaging area and the supportless region are 42 × 42mm2 and 30mmφ respectively. The goal of the thickness of the depletion layer is 300μm, which enables us to cover the energy range of 0.3 - 25 keV. The evaluation model 'CCD-NeXT1' with the size of 24 × 48mm2 shows no performance change due to the thinning process. The test model of P-channel CCD was confirmed to have high quantum efficiency above 10 keV with an equivalent depletion layer of 300m.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Japan's 6th X-ray satellite mission NeXT has completed pre-Phase-A study, and is waiting to advance to Phase-A/B. The X-Ray Telescope System on board NeXT covers wide energy range from 0.3 to 80 keV. The paper reviews current status on design and technology of the mission as written in the NeXT Mission Proposal on Oct. 2005.

DOI： 10.1117/12.671341

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We have developed advanced thin-foil substrates with a two-stage reflector for a large X-ray telescope. We successfully formed a magnesium foil with a figure error of a peak-to-peak value of 60 mu m. This figure error has allowed a replication method in order to obtain smooth surface. We made a glass mandrel precisely shaped Wolter type-I optics by using the ELID method-, then applied the replication to a 200 mm length aluminum foil at Nagoya University. After the replication, the figure error of the foil was improved by as much as factor 10. We evaluated the image quality of the replicated foil by using a collimated optical light at Ehime University, and we demonstrated the potential of the replication method. We report a current status of the development of the replication method.

DOI： 10.1117/12.670628

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We present the results of timing analysis of the XMM-Newton observation of the Seyfert 2 galaxy NGC 6300. The hard X-ray spectrum above 2 keV consists of a Compton-thin absorbed power law, as is often seen in Seyfert 2 galaxies. We clearly detected rapid time variability on a timescale of about 1000 s from the light curve above 2 keV. The excess variance of the time variability (sigma(rms)(2)) is calculated to be similar to 0.12, and the periodogram of the light curve is well represented by a power-law function with a slope of 1.75. In contrast to previous results from Seyfert 2 nuclei, these variability characteristics are consistent with those of Seyfert 1 galaxies. This consistency suggests that NGC 6300 has a black hole mass and accretion properties similar to Seyfert 1 galaxies. Using the relation between time variability and central black hole mass by Hayashida et al., the black hole mass of NGC 6300 is estimated to be similar to 2.8 x 10(5) M-circle dot. Taking the uncertainty of this method into account, the black hole mass is less than 10(7) M-circle dot. Taking the bolometric luminosity of 3.3 x 10(43) ergs s(-1) into consideration, this yields an accretion rate of &gt; 0.03 of the Eddington value, comparable to estimates from Seyfert 1 galaxies using this method. The time variability analysis suggests that NGC 6300 actually has a Seyfert 1 nucleus obscured by thick matter and more generally provides a new pillar of support for the unified model of Seyfert galaxies based on obscuration.

DOI： 10.1086/433161

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

Astro-E2 is the fifth Japanese X-ray astronomical satellite and will be launched in 2005. The Astro-E2 X-ray Imaging Spectrometers (XISs) consist of four sets of X-ray CCD cameras. Each CCD camera has an imaging area of 1024 x 1024 pixels and covers a region of 18' x 18' on the sky combined with an X-ray Telescope. One XIS will utilize backside illuminated (BI) CCDs, and the other three will be equipped with front-side illuminated (171) CCDs. The BI CCD has a higher quantum efficiency than the FI CCD below 2 keV, while the FI CCD is more sensitive to X-rays above 5 keV than the BI CCD. Both types of the CCDs have nearly the same energy resolution (full-width at half-maximum (FWHM) =similar to 130 eV at 6 keV). All four cameras have a charge injection capability and Fe-55 calibration sources, and we can correct the change of the gain and recover the degradation of the energy resolution due to radiation damage caused by cosmic rays. The sensors are cooled to -90 degrees C to minimize thermal noise in orbit. The low temperature is also helpful to reduce the influence of the radiation damage. (c) 2005 Elsevier B.V. All rights reserved.

DOI： 10.1016/j.nima.2005.01.076

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We give an overview, the current status and future plan of the development of the Soft X-ray Imager (SXI) onboard the NeXT (Non-thermal Energy eXploration Telescope) satellite proposed to be launched around 2010. The SXI is a back-illuminated supportless CCD (a combination of "back-illuminated CCD" and "supportless CCD") whose imaging area size and the supportless region are 42 mm x 42 mm and 30 mm phi, respectively. The goal of the depletion layer of the CCD is 300 mu m, which enable us to cover the X-ray energy range of 0.5-20 keV. The first test model of the supportless CCD shows no performance change due to the thinning process of the CCD. We have already started processing the evaluation model 'CCD-NeXT1', which will be completed at the end of 2004. We are also studying the camera system, the focal plane assembly including thermal electric cooler (TEC) and electronics as well as the CCD chip. (c) 2005 Published by Elsevier B.V.

DOI： 10.1016/j.nima.2005.01.080

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Observations of the Seyfert 2 and starburst galaxy NGC 7130 with the Chandra X-Ray Observatory illustrate that both of these phenomena contribute significantly to the galaxy's detectable X-ray emission. The active galactic nucleus (AGN) is strongly obscured, buried beneath column density N-H &gt; 10(24) cm(-2), and it is most evident in a prominent Fe Kalpha emission line with equivalent width greater than 1 keV. The AGN accounts for most (60%) of the observed X-rays at energy E &gt; 2 keV, with the remainder due to spatially extended star formation. The soft X-ray emission is strong and predominantly thermal on both small and large scales. We attribute the thermal emission to stellar processes. In total, the AGN is responsible for only one-third of the observed 0.5-10 keV luminosity of 3 x 10(41) ergs s(-1) of this galaxy and less than half of its bolometric luminosity. Starburst/AGN composite galaxies like NGC 7130 are truly common, and similar examples may contribute significantly to the high-energy cosmic X-ray background while remaining hidden at lower energies, especially if they are distant.

DOI： 10.1086/425913

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We report on a 100 ks Suzaku observation of the bright, nearby (z = 0.008486) Seyfert 1.9 galaxy MCG -5-23-16. The broad-band (0.4-100keV) X-ray spectrum allows us to determine the nature of the high energy emission with little ambiguity. The X-ray continuum consists of a cutoff power-law of photon index Γ = 1.9, absorbed through Compton-thin matter of column density NH = 1.6 × 1022cm-2. A soft excess is observed below 1 keV and is likely a combination of emission from scattered continuum photons and distant photoionized gas. The iron K line profile is complex, showing narrow neutral iron Kα and Kβ emission, as well as a broad line which can be modeled by a moderately inclined accretion disk. The line profile shows either the disk is truncated at a few tens of gravitational radii, or the disk emissivity profile is relatively flat. A strong Compton reflection component is detected above 10 keV, which is best modeled by a combination of reflection off distant matter and the accretion disk. The reflection component does not appear to vary. The overall picture is that this Seyfert 1.9 galaxy is viewed at moderate (∼ 50°) inclination through Compton-thin matter at the edge of a Compton-thick torus covering ∼ 2π steradians. consistent with unified models. © 2007. Astronomical Society of Japan.

DOI： 10.1093/pasj/59.sp1.s301

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We are studying on a press forming of a 0.3-mm-thick foil in order to make advanced thin-foil substrates with a two-stage reflector for large X-ray telescopes. Aluminum alloy has been used as a material for thin-foil substrates. We propose a use of Mg foil as lightweight substrates, since more lightweight material is necessary for building the large telescopes. Furthermore, we are making a two-stage reflector with a stage 200 mm long, since a long substrate has an advantage for fabrication of large X-ray telescopes. After various experiments, we formed a Mg foil with a figure error of +/-20 mu m. This large figure error can be removed by a replication method. We also made an evaluation system of an image quality by using a Newtonian telescope. The evaluation system can generate a collimated optical light with a diameter of 450 mm and with a parallelism of about 4 &apos;&apos;. Using this system, we found that an image quality of our Mg foil was similar to that of the ASCA foils.

DOI： 10.1117/12.613829

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We present results from a half-day observation by XMM-Newton of the nucleus of the nearby Seyfert 2 galaxy NGC 6300. The X-ray spectrum of the nucleus consists of a heavily absorbed hard component dominating the 3-10 keV band and a soft component seen in the 0.2-2 keV band. In the hard band, the spectrum is well fitted by a power-law model with photon index of 1.83 +/- 0.08 attenuated by a Compton-thin absorber (N-H similar or equal to 2.2 x 10(23) cm(-2)). A narrow iron line is detected at 6.43(-0.02)(+0.01) keV with an equivalent width of similar to 150 eV; the line velocity width is marginally resolved to be sigmasimilar to 60 eV. The soft emission can be modeled as a power law and may be emission scattered by surrounding plasma. Rapid and high-amplitude variability is observed in the hard X-ray band, whereas both the iron line and the soft emission show no significant variability. It is suggested that the nucleus has experienced an overall long-term trend of decreasing hard X-ray intensity on a timescale of years. We discuss the origins of the spectral components.

DOI： 10.1086/425566

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

Observations of the Seyfert 2 and starburst galaxy NGC 5135 with the Chandra X-Ray Observatory demonstrate that both of these phenomena contribute significantly to its X-ray emission. We spatially isolate the active galactic nucleus (AGN) and demonstrate that it is entirely obscured by column density N-H&gt;10(24) cm(-2), detectable in the Chandra bandpass only as a strongly reprocessed weak continuum and a prominent iron Kalpha emission line with equivalent width of 2.4 keV. Most of the soft X-ray emission, both near the AGN and extending over spatial scales of several kpc, is collisionally excited plasma. We attribute this thermal emission to stellar processes. The AGN dominates the X-ray emission only at energies above 4 keV. In the spectral energy distribution that extends to far-infrared wavelengths, nearly all the emergent luminosity below 10 keV is attributable to star formation, not the AGN.

DOI： 10.1086/380836

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

Investigating the X-ray luminosity function of AGNs in different redshifts is very important in understanding growth of super massive black holes in centers of galaxies over the cosmological time scale. As a part of this, we are investigating the statistics of the X-ray spectral properties of a complete flux-limited sample of bright AGNs. The purpose of this investigation is to provide the present-day constraint on the evolution of absorbed and unabsorbed AGNs. and to constrain the AGN population synthesis model of the total X-ray background.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON-ELSEVIER SCIENCE LTD  

We have built a prototype of thin-foil substrates for the future mission with a large X-ray telescope. In future X-ray missions, the understanding of the early universe to reveal the evolution of the universe will become an important issue. For this purpose, large telescopes with high-spatial resolution up to 10" are required. Using a stamping die with high accuracy, we have successfully press-formed thin-foil substrates into an almost accurate form of the Wolter type-I optics, which reflect X-rays twice with their confocal paraboloidal and hyperboloidal reflectors. The accuracy of the shape has reached to &lt;15 mum. (C) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.

DOI： 10.1016/j.asr.2003.03.058

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We found short time variability (Deltat similar to 1 ks) of NGC 6300 in the 2-10 keV band with XAM-Newton. Its normalized power spectral density can be expressed by a power-law function of frequency with a slope of similar to -1.7. These results are similar to those of Seyfert 1 galaxies. Using the relation between time variability and central black hole mass, we estimate the black hole mass of about 3 x 10(5) M-circle dot. The time variability analysis suggests that NGC 6300 actually has a Seyfert 1 nucleus obscured by a thick matter.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

The dwarf starburst galaxy NGC 1569 was observed for 96.8 ks with Chandra. We detected several variable X-ray point sources in the central region of NGC 1569. Inparticular, two bright point sources, CXOU 043048.1+645050 and CXOU 043048.6+645058, exhibit a prominent variability in time. Fitting with the disk blackbody model, we find that CXOU 043048.1+645050 may be a stellar mass black hole with similar to 20Mcircle dot. From the fact that CXOU 043048.6+645058 has a short time variability and flat spectrum, we concluded that this source may be a neutron star binary. We calculated the luminosity ratio of the soft X-ray band to other energy bands, and find that NGC 1569 has a typical luminosity ratio found in starburst galaxies.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We are studying on a press forming of a 0.3-mm-thick foil in order to make advanced thin-foil substrates with a two-stage reflector for large X-ray telescopes. We press-formed one sheet of aluminum foil using a stamping die with high accuracy, and then obtained a two-stage reflector with a length of 100 mm/stage. The accuracy of its shape along the axial direction reached to 10 mum. Since long substrate has an advantage for fabrication of large X-ray telescopes, we are making a two-stage reflector with a stage 200 mm long. The stamping die for the long substrate was processed by the ELID method. We will perform a press-forming in this summer. In order to evaluate the press-formed substrate, we have made a surface measurement system. It is possible to response to a fabrication of the substrate quickly.

DOI： 10.1117/12.550325

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

From the analysis of a similar to100 ks Chandra observation of the dwarf starburst galaxy NGC 1569, we have found that the X-ray point sources CXOU 043048.1 + 645050 and CXOU 043048.6 + 645058 show significant time variability. During this observation, the X-ray flux of CXOU 043048.1 + 645050 increased by 10 times in only 2 x 10(4) s. Since the spectrum in its bright phase was fitted with a disk blackbody model with kT(m) approximate to 0.43 keV and the bolometric luminosity is L-bol approximate to 10(38) ergs s(-1), this source is an X-ray binary with a stellar mass black hole. Since the spectrum in its faint phase was also fitted with a disk blackbody model, the time variability can be explained by a change of the accretion rate onto the black hole. The other variable source, CXOU 043048.6+645058, had a flat spectrum with a photon index of similar to1.6. This source may be an X-ray binary with an X-ray luminosity of several times 10(37) ergs s(-1). In addition, three other weak sources showed possible time variability. Taking all of the variability into account may suggest an abundant population of compact X-ray sources in NGC 1569.

DOI： 10.1086/377090

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Language：English   Publisher：OXFORD UNIV PRESS  

We observed the radio-quiet QSO Kaz 102 (z = 0.136) with ASCA as a part of our program for a complete spectral characterization of hard X-ray selected AGNs. We found that Kaz 102 shows unusual spectral properties. A simple power-law with absorption in our Galaxy gave a satisfactory description of the spectrum. However, it showed a very hard photon index of Gamma similar to 1.0 with no sign of deep absorption or a prominent spectral feature. We further explored the Compton reflection with the Fe Kalpha line and warm absorber models for hardening the spectra. Both gave statistically satisfactory fits. However, the Compton reflection model requires a very low metal abundance (0.03-0.07 in solar units). The warm absorber model with no direct component is preferred, and gave a very high ionization parameter of xi similar to 10(2.3). If this is the case, the values of xi, warm absorber column density, and variability over similar to 10 yr may suggest that the warm absorber resides in the broad-line region and crosses the line of sight to the central X-ray source.

DOI： 10.1093/pasj/55.2.L11

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We propose a method to make advanced thin-foil substrates for an X-ray telescope by press forming. Walter Type-I optics, which reflect X-rays twice with their confocal paraboloidal and hyperboloidal reflectors, have commonly been used in X-ray astronomy. However, it is difficult to make substrates for a large X-ray telescope with a high imaging quality. By forming two reflectors from one thin substrate, the accuracy of the angle between two reflectors is determined by the accuracy of a mandrel or a stamping die. We made a stamping die using a precision processing method at RIKEN. After several improvements of our pressing method, we have obtained the substrates with a figure error &lt; 15 mum., which corresponds to an angular resolution of about 2' at the focal plane, although a small waviness was found on the mirror surface. We also propose a new holding method of the foil to reduce a displacement of the foil positions. The foil is tightly held with three thin-supports with a thickness of 0.3 mm. We made the test model of a mirror housing, and found that the foil position was determined with or sigma similar to 12 mum.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We present a new method for estimating the thickness of the depletion layer of an X-ray CCD without a calibrated X-ray source. It is known that a high-energy particle continuously loses its energy when it passes through a material, and that its total-energy loss in a thin material depends on the thickness of the material. We irradiated a Hamamatsu-CCD (CCD-CREST Deep 1) with a conversion beta-ray source Bi-207 which emits monoenergetic beta-rays, then obtained an energy-loss distribution. In comparison with an energy-loss distribution simulated with Geant4, we found that the CCD-CREST has a depletion layer thickness of similar to 6.7 mum, which is consistent with the result using a calibrated X-ray source. Since it is difficult to obtain a calibrated X-ray source, our method is useful for estimating a depletion layer thickness. (C) 2002 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-9002(02)01612-1

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We analyze X-ray spectra of heavily obscured (N-H &gt; 10(24) cm(-2)) active galaxies obtained with Chandra, concentrating on the iron Kalpha fluorescence line. We measure very large equivalent widths in most cases, up to 5 keV in the most extreme example. The geometry of an obscuring torus of material near the active galactic nucleus (AGN) determines the Fe emission, which we model as a function of torus opening angle, viewing angle, and optical depth. The starburst/AGN composite galaxies in this sample require small opening angles. Starburst/AGN composite galaxies in general therefore present few direct lines of sight to their central engines. These composite galaxies are common, and their large covering fractions and heavy obscuration effectively hide their intrinsically bright X-ray continua. While few distant obscured AGNs have been identified, we propose to exploit their signature large Fe Kalpha equivalent widths to find more examples in X-ray surveys.

DOI： 10.1086/342092

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We observed a nearby merger remnant NGC 7252 with the X-ray satellite ASCA and detected X-ray emission with the X-ray flux of (1.8 +/- 0.3) x 10(-13) ergs s(-1) cm(-2) in the 0.5-10 keV band. This corresponds to the X-ray luminosity of 8.1 x 10(40) ergs s(-1). The X-ray emission is well described with a two-component model: a soft component with kT = 0.72 +/- 0.13 keV and a hard component with kT &gt; 5.1 keV. Although NGC 7252 is referred to as a dynamically young protoelliptical, the 0.5-4 keV luminosity of the soft component is about 2 x 10(40) ergs s(-1), which is low for an early-type galaxy. The ratio of L-X/L-FIR suggests that the soft component originated from the hot gas due to star formation. Its low luminosity can be explained by the gas ejection from the galaxy as galaxy winds. Our observation reveals the existence of hard X-ray emission with the 2-10 keV luminosity of 5.6 x 10(40) ergs s(-1). This may indicate the existence of nuclear activity or an intermediate-mass black hole in NGC 7252.

DOI： 10.1086/338694

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We analyzed six low-luminosity active galactic nuclei (hereafter LLAGNs), which consist of two bright LINERS (low-ionization nuclear emission line region) with broad Hoe, and of four bright low-luminosity Seyferts observed by the X-ray satellite ASCA. We examined the time variabilities of these targets, and found that most targets show no significant time variabilities, although these galaxies belong to LLAGNs. By applying Fourier analysis to their light curves in the 2-10 keV band, we obtained the lower limits of their time variability scales, which correspond to their central black hole masses greater than several times 10(6) M-circle dot. Our result suggests that these LLAGNs are harbors of super-massive black holes. but the emitting powers are only &lt; 1% of the Eddington luminosities of the central engines in the LLAGNs due to their small accretion rates. Since a black hole would grow by mass accretion, it is hard to create Such a super-massive black hole under a small accretion rate. Therefore, the mass-accretion rates in the past must have been larger than those at present, and the galaxies have probably been as luminous as QSOs. This will be a hint to find out the cause of the lack of QSOs in the local universe.

DOI： 10.1093/pasj/53.4.647

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present results from observations of the most famous starburst galaxy M82 with the High-Resolution Camera on board the Chandra X-Ray Observatory. We found nine sources in the central 1' x 1' region, but no source was detected at the galactic center. Comparing the observations on 1999 October 28 and on 2000 January 20, we found that four of the nine sources showed significant time variability. In particular, CXOM82 J095550.2+694047, which is 9 " away from the galactic center, showed extremely large time variability. We conclude that this source is the origin of the hard X-ray time variability of M82 detected with ASCA. Assuming a spectral shape obtained by the ASCA observation, its luminosity in the 0.5-10 keV band changed from 1.2 x 10(40) ergs s(-1) on 1999 October 28 to8.7 x 10(40) ergs s(-1) on 2000 January 20.

DOI： 10.1086/318878

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AMER INST PHYSICS  

We report here a new event analysis method "two-dimensional Gaussian function fitting" for the X-ray photon count CCD camera. A grade method employed in the ASCA satellite is widely used in the event analysis which excluded the extended event as non X-ray event. Our new method can save extended X-ray events without degradation of the energy resolution and without decrease of the background rejection efficiency. It increases the detection efficiency of Xray photons by 7.5% at 7 keV and 25% at 12.5 keV, respectively. We will employ this method in the X-ray CCD camera onboard ASTRO-E to be launched in February, 2000.

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Language：English   Publishing type：Research paper (international conference proceedings)  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Walter Type-I optics, which reflect X-rays twice with their confocal paraboloidal and hyperboloidal reflectors, have commonly been used in X-ray astronomy. These two reflectors usually consist of two thin substrates with conical shapes in order to obtain a large effective area above 2 keV. However, such telescopes tend to have poorer imaging quality clue to approximation to conical shapes and misalignment of the two substrates. In order to reduce the degeneration in the imaging quality, we formed two reflectors from one thin substrate. The accuracy of the angle between two reflectors is determined by the tolerance of the mandrel used to form the thin foil substrate. At RIKEN we make the mandrel using a precision processing method. Here we present the results of our preliminary experiment on substrate forming.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：ASTRONOMICAL SOC PACIFIC  

We performed the evaluation of domestic X-ray CCDs and compared with XIS, onboard Chandra and ASTRO-EII. We evaluate them with analog electronics made for XIS. After fine tuning of gain, we found that the energy resolution of the CCD is about 135eV at 5.9 keV (FWHM) and the read-out noise of about 6 electron. This result shows that domestic X-ray CCDs are as good as XIS except for the read-out noise.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We analyze the 0.5-10 keV spectra of six Seyfert 2 galaxies observed with the X-ray satellite ASCA: Mrk 3, Mrk 348, Mrk 1210, Mrk 477, NGC 7212, and Was 49b. These galaxies were selected based on their possession of optical polarized broad lines. In the 2-10 keV band, their spectra are heavily absorbed, with 2-10 keV absorption-corrected X-ray luminosities ranging from 10(42) to 10(43) ergs s(-1). The observed X-ray emission is generally only about 1/10 that predicted based on their known infrared and HE luminosities. This apparent X-ray weakness can be understood if a considerable fraction of the nuclear activity is completely blocked from view by thick matter along our line of sight to the nucleus. All of these galaxies possess significant soft X-ray emission whose origin appears to be scattered light from their nuclear emission. Based on this hypothesis, we estimate a typical scattering efficiency for X-rays to be about 10%. This efficiency is larger than the few percent found for ordinary Seyfert 2 galaxies with no report of optical polarized broad lines. A large scattering efficiency is best explained by an apparent weakness of the hard X-ray luminosity rather than unusually strong scattered light in the soft band. When we estimate the scattering efficiency using the intrinsic luminosity derived assuming that Compton scattering dominates the hard X-ray spectrum, as opposed to a purely absorbed nuclear continuum, the efficiency can be less and is similar to that of ordinary Seyfert 2 galaxies. Since the difference between our sample and ordinary Seyfert 2 galaxies can be explained by the difference of viewing angle, the similar scattering efficiency suggests the existence of a scattering region that is larger than the putative dusty torus.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We have developed a CCD calibration system using fluorescent X-ray lines with energies ranging from 1.49 keV (Al K alpha) to 11.2 keV (Se Ka). The absolute X-ray flux is calibrated by a gas proportional counter, while the emerging spectra are monitored by solid-state silicon detectors. In order to suppress contaminating X-rays in the fluorescence spectra, mechanical collimators were set in the X-ray beam line, high-purity targets for fluorescent lines were used, and band-pass filters were put on the X-ray beam line. As for the purity of the fluorescent X-rays, the typical purity achieved was similar to 98%. (C) 2000 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-9002(00)00306-5

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We report infrared spectroscopy of the prototypical Seyfert 2 galaxy NGC 1068, aiming at detection of broad components of hydrogen recombination lines that originate in the obscured broad-line region. Using the Short Wavelength Spectrometer on board the Infrared Space Observatory, we have observed for the first time the regions of B beta 2.626 mu m and Pf alpha 7.460 mu m, and present improved data for B alpha 4.052 mu m No significant broad components are detected, implying an equivalent visual extinction to the broad-line region of at least 50 mag and an obscuring column density of at least 10(23) cm(-2). While consistent with a highly obscured broad-line region, as required by the classical unified scenario, these limits are not yet significant enough to discriminate strongly between different torus models or to constrain properties of the gas causing the very large X-ray obscuration. We discuss the systematic limitations of infrared broad-line region searches and suggest that B alpha may often be the most favorable transition for future searches.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON PRESS LTD  

We investigate spectral variations dependent on short timescale variations in the Seyfert galaxy MCG -6-30-15 using data obtained with ASCA in 1994. Spectral hardening of the continuum spectrum during a large flare lasting for similar to 5 x 10(4) sec was observed. Such spectral hardening is commonly observed in stellar black hole candidates. This and other similarities in X-rays between these objects suggest their time variations have the same origin. We have also found that the narrow iron K alpha line is more prominent in the decay phase of the flare than in the rise phase. This implies time lags of the narrow iron-line component behind the continuum component, which indicate that the narrow iron K alpha line is present in the outer region (similar to 1000 r(s)) of the accretion disk. (C) 2000 COSPAR. Published by Elsevier Science Ltd.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON PRESS LTD  

We present results of ASCA deep exposure observations and optical identifications of the hardest X-ray source discovered in the ASCA Large Sky Survey project, designated as AX J131501+3141. AX J131501+3141 exhibits a large X-ray absorption of N-H = (6(-2)(+4)) x 10(26) H m(-2). The observed X-ray flux was time variable by a factor of 30% in 0.5 year: F-X (2-10 keV) =(4.8-6.2) x 10(-16) J m(-2) s(-1). From optical photometric and spectroscopic observations, we found one galaxy with R = 15.6 mag in the X-ray error circle, whose emission line ratios are similar to those found in type 2 Seyfert galaxies. Its redshift is determined to be 0.07, hence the absorption-corrected X-ray luminosity is L-X similar to 2 x 10(36) J s(-1) (2-10 keV). Accordingly, we conclude that AX J131501+3141 is a type 2 Seyfert galaxy. Discovery of such a low flux and highly absorbed X-ray source could have a significant impact on the origin of the cosmic X-ray background. (C) 2000 COSPAR. Published by Elsevier Science Ltd.

DOI： 10.1016/S0273-1177(99)00853-4

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Language：English  

DOI： 10.1016/S0273-1177(99)00860-1

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We present the results of the mapping observations of the northwest region of the Virgo cluster. The X-ray spectra can be represented by a single-temperature plasma. The temperature of the intracluster medium decreases with radius from 0′ to 50′, and it becomes almost constant beyond the 50′ radius. The metal abundances also decrease with radius from 0′ to 40′, then become constant beyond the radius of 40′. These temperature and abundance profiles can be clues to investigate the cluster formation history and cosmological parameters. © 2000 COSPAR. Published by Elsevier Science Ltd.

DOI： 10.1016/S0273-1177(99)00808-X

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON PRESS LTD  

We have assembled data for Seyfert 2 galaxies which have polarized broad lines. In the 2-10keV band, we find heavily absorbed X-ray emission with an absorbing column density of about 10(23) cm(-2). The X-ray luminosity ranges from 10(42) to 10(43) erg s(-1) in the 2 - 10 keV band. We conclude that all of our targets have obscured nuclei. Our results suggest a good correlation between X-ray observation and spectropolarimetry.
We also detect soft X-ray emission, and find that the flux ratio to the obscured hard component is about 10%, which is larger than those of Seyfert 2 galaxies for which existence of polarized broad lines have not been reported. We discuss the origin of the soft component. (C) 2000 COSPAR. Published by Elsevier Science Ltd.

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Language：Japanese   Publishing type：Research paper (scientific journal)   Publisher：Proceedings of SPIE - The International Society for Optical Engineering  

Soft X-ray response of X-ray Imaging Spectrometers (XIS) for the Astro-E satellite is measured with a grating spectrometer system at Osaka. First, relation between incident X-ray energy and output pulse height peak (E-PH relation) is examined with an SX grating. It is found that jump in the E-PH relation around Si-K edge is at most 2.7 eV. Second, quantum efficiency (QE) of the XIS in 0.4-2.2 kev range is measured relatively to the reference CCD of which absolute QE was calibrated with a gas proportional counter. The QE is fitted with a model in which CCD gate structures are considered. Systematic error on the QE results is estimated by referring an independent measurement. Third, tuning and improvement of the response function is performed. We employ six components to reproduce the response profile of the XIS. In this paper, improvement of one component which is originated in the events absorbed in the channel-stop is presented. Neverthless, Astro-E was lost due to the launch failure. We overview the XIS project in its flight model phase, modified points of the design, problems and solutions etc., in order to be utilized in a possible recovery of the satellite.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Soft X-ray response of X-ray Imaging Spectrometers (XIS) for the Astro-E satellite is measured with a grating spectrometer system at Osaka. First, relation between incident X-ray energy and output pulse height peak (E-PH relation) is examined with an SX grating. It is found that jump in the E-PH relation around Si-K edge is at most 2.7 eV. Second, quantum efficiency (QE) of the XIS in 0.4-2.2 keV range is measured relatively to the reference CCD of which absolute QE was calibrated with a gas proportional counter. The QE is-fitted with a model in which CCD gate structures are considered. Systematic error on the QE results is estimated by referring an independent measurement. Third, tuning and improvement of the response function is performed. We employ six components to reproduce the response profile of the XIS. In this paper, improvement of one component which is originated in the events absorbed in the channel-stop is presented.
Neverthless, Astro-E was lost due to the launch failure. We overview the XIS project in its flight model phase, modified points of the design, problems and solutions etc., in order to be utilized in a possible recovery of the satellite.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

We report on the hard X-ray response of the CCD detector for the X-ray imaging spectrometer (XIS), to be launched on the next Japanese X-ray Astronomical Satellite, ASTRO-E, in February 2000. XIS is prepared by an international team, comprised of MIT (USA), ISAS, Osaka University and Kyoto University (JAPAN). We have evaluated the X-ray response of the XIS in its high-energy band (1.5-10 keV). Data from the fluorescent line emission of Al, Cl, Ti, Ni, Fe, Zn, Se were used to construct the response function of the CCD detectors. Details of the response function - including the energy-scale, linearity, energy resolution, quantum efficiency -, are given as a function of incident X-ray energy. We find that the tail component of high-energy photopeaks are produced by events with incomplete charge collection. We also conclude that the size of the charge clouds can be estimated using the shapes of the tail components. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-9002(99)00601-4

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ELSEVIER SCIENCE BV  

In the course of developing a fast readout system of an X-ray CCD camera with low noise using HPK-CCD, we have succeeded in making a clock generator to read data from a CCD with the speed of 2 M pixel/s. This generator is fabricated from commercially available products in order to simplify the manufacturing procedure. To determine the noise of the system, we are evaluating the noise from each part which conceivably contributes. It is known that the readout noise depends on the clock speed. Thus, to begin with, we measured the dependency of the system noise from the ADC in the data acquisition system on its clock speed. (C) 1999 Elsevier Science B.V. All rights reserved.

DOI： 10.1016/S0168-9002(99)00616-6

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

Scanning and pointed Rossi X-Ray Timing Explorer (RXTE) observations of the nearby Seyfert 2 galaxy NGC 6300 reveal that it is a source of hard X-ray continuum and large equivalent-width Fe K alpha emission. These properties are characteristic of Compton reflection-dominated Seyfert 2 galaxies. The continuum can be modeled as Compton reflection; subsolar iron abundance is required, and a high inclination is preferred. However, the poor energy resolution of RXTE means that this description is not unique, and the continuum can also be modeled using a "dual absorber," i.e., a sum of absorbed power laws. Observations with higher energy resolution detectors will cleanly discriminate between these two models. Optical observations support the Compton reflection-dominated interpretation as L-X/L-[O III] is low. NGC 6300 is notable because with F2-10 approximate to 6.4 x 10(-12) ergs cm(-2) s(-1), it is the second brightest such object known.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

To address the nature of the Fe K alpha line profile and the soft X-ray excess in the Seyfert 2 galaxy NGC 5506, we have performed a broadband X-ray analysis of data obtained with ASCA and ROSAT. Variations of up to 70% in the 2-10 keV band flux are detected during a 1 day ASCA observation performed in 1997 January, while no significant change in the 2-10 keV continuum shape is found. The ASCA spectrum consists of an absorbed power law, a "soft excess" below 2 keV, and an Fe Ka emission line at 6.4 keV. The "soft excess" can be well described either by thermal emission from very low-abundance material at a temperature kT similar or equal to 0.8 keV or by scattered/leaking flux from the primary power law plus a small amount of thermal emission. The luminosity of the thermal emission in the former case is 1.2 x 10(40) ergs s(-1) over the 0.5-2 keV band, while the excess is similar to 1% of the intrinsic hard X-ray continuum in the latter case. Analysis of ROSAT HRI data confirms that the soft X-ray emission is extended on kpc scales in this object, and the extended component may account for most of the soft X-ray excess observed by the ASCA. The result suggests that in type 2 active galactic nuclei (AGNs), the "soft excess" comes at least partly from an extended region, causing a serious problem for the model in which the source is partially covered. We argue that the generally low abundances are a drawback for the single temperature thermal model and favor a scattering-dominated model. The scatterer is likely to be relatively cold (kT much less than 1 keV) in this object.
The Fe K alpha profile is complex and cannot be satisfactorily modeled by a single Gaussian. Models of either double Gaussians, or a narrow Gaussian plus a line from a relativistic accretion disk viewed at an inclination of about 40 degrees +/- 10 degrees provide good fits to the data. However, the inclination of the disk can be substantially larger if there is a small amount of excessive Fe K edge absorption. The intermediate inclinations for narrow-line X-ray galaxies are consistent with a model in which the inner accretion disk is aligned with an outer obscuring torus.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We introduce a new method of event analysis with the X-fay CCD camera (XIS) onboard the next Japanese Xray astronomical satellite, Astro-E. In the ordinary method (ASCA, AXAF),we used "grade" classification; we distinguished the X-ray events from background events by referring the shape and the extent of the charge-split pixel, because non X-ray events spread to many pixels. However, at the same time, this method lowered the quantum efficiency of high energy X-ray photons which also extend far several pixels. We tried the method with 2-dimension image-fitting of each event. We succeeded in rejecting non X-ray events by the extent of fitted function. We achieved higher detection efficiency by 10% than the grade method for hard X-rays above 8 keV, while the energy resolution becomes worse by 0-8%. The improvements and the problems of this new method are also presented.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON PRESS LTD  

I reviewed recent X-ray observations of LINERs and low luminosity AGNs (LLAGNs) with the Japanese X-ray satellite ASCA. The main purpose of the ASCA observations was to reveal the X-ray properties of these galaxies, especially nuclear activity. ASCA observed 15 LLAGNs and found nuclear X-ray emission for 13 LLAGNs except NGC 1672 and NGC 4501. On the other hand, compact hard X-ray emission probably associated with nuclear activity was found in seven LINERs, and six LINERs among seven have a broad H alpha line. This result suggests that the excitation mechanism of these LINERs is photoionization. Soft X-ray emission from LINERs was found, and the emission can be associated with the starburst phenomenon in LINERs
I characterized the variability time scale using the Fourier timing analysis and deduced the lower limit of central black hole mass. The black hole masses are greater than 10(7) solar mass, which are consistent with those of high luminosity AGNs. However, the,X-ray luminosity of LLAGNs and LINERs are only 1/1000 of that of high-luminosity AGNs. This indicates that LLAGNs and LINERs may turn into AGNs if fuel is supplied to the central black hole. (C) 1999 COSPAR. Published by Elsevier Science Ltd.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON PRESS LTD  

Results of the analysis of the ASCA and ROSAT HRI data are presented. We find: (1) The flux in the 2-10 keV band varies by a factor of 70% during 1 day of ASCA observation. (2) The ASCA spectrum consists of a main power-law typical of Seyfert 1 galaxies absorbed by a column density similar or equal to 3 x 10(22) cm(-2), a soft excess below 2 keV and an Fe K alpha emission line. (3) The Fe K alpha line profile is complicated and can be well fitted with a double gaussian or a narrow gaussian plus an emission line from a relativistic acrretion disk viewed at an inclination of similar or equal to 40 degrees. (4) The soft X-ray can be described by either thermal emission from very low abundant gas at temperature kT similar or equal to 0.8 keV or scattered/leaking flux from the primary power-law plus a small amount of thermal emission. (5) ROSAT HRI data reveal that the soft X-ray emission is extended on kpc scales, and the extent emission may account for the ASCA soft excess. These results are consistent with predictions from the unification model. (C) 1999 COSPAR. Published by Elsevier Science Ltd.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present results of the ASCA deep-exposure observations of the hardest X-ray source discovered in the ASCA Large Sky Survey (LSS) project, designated as AX J131501 + 3141. We extract its accurate X-ray spectrum, taking into account the contamination from a nearby soft source (AX J131502 + 3142) separated from it by only 1'. AX J131501 + 3141 exhibits a large absorption of N-H = 6(-2)(+4) x 10(22) H cm(-2), with a photon index Gamma = 1.5(-0.6)(+0.7). The 2-10 keV flux was about 5 x 10(-13) ergs cm(-2) s(-1), and was time variable by a factor of 30% in 0.5 yr. From the highly absorbed X-ray spectrum and the time variability, as well as the results of the optical follow-up observations, we conclude that AX J131501 + 3141 is a type 2 Seyfert galaxy. Discovery of such a low-flux and highly absorbed X-ray source could have a significant impact on our understanding of the origin of the cosmic X-ray background.

DOI： 10.1086/306158

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

NGC 7582 is a candidate prototype of the narrow line X-ray galaxies (NLXGs) found in deep X-ray surveys. An ASCA observation shows the hard (&gt;3 keV) X-ray continuum of NGC 7582 drops 40% in similar to 6 ks, implying an active galactic nucleus (AGN), while the soft band (&lt;3 keV) does not drop in concert with the hard continuum, requiring a separate component. The X-ray spectrum of NGC 7582 also shows a clear 0.5-2 keV soft (kT = 0.8(-0.3)(+0.9) keV or Gamma = 2.4 +/- 0.6; L-x = 6 x 10(40) ergs s(-1)) low-energy component, in addition to a heavily absorbed [N-H = (6 +/- 2) x 10(22) cm(-2)] and variable 2-10 keV power law [Gamma = 0.7(-0.4)(+0.3); L-x = (1.7-2.3) x 10(42) ergs s(-1)]. This is one of the flattest 2-10 keV slopes in any AGN observed with ASCA. (The ROSAT HRI image of NGC 7582 further suggests extent to the SE.) These observations make it clear that the hard X-ray emission of NGC 7582, the most "narrow-line" of the NLXGs, is associated with an AGN. The strong suggestion is that all NLXGs are obscured AGNs, as hypothesized to explain the X-ray background spectral paradox. The separate soft X-ray component makes NGC 7582 land by extension other NLXGs) detectable as a ROSAT source.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL SCIENCE LTD  

We present results of the ASCA observation of the Seyfert 2 galaxy NGC 4507. The 0.5-10 keV spectrum is rather complex and consists of several components: (i) a hard X-ray power law heavily absorbed by a column density of about 3 x 10(23) cm(-2), (ii) a narrow Fe K alpha line at 6.4 keV, () soft continuum emission well above the extrapolation of the absorbed hard power law and (iv) a narrow emission line at similar to 0.9 keV. The line energy, consistent with highly ionized neon (Ne IX), may indicate that the soft X-ray emission is derived from a combination of resonant scattering and fluorescence in a photoionized gas. Some contribution to the soft X-ray spectrum from thermal emission, as a blend of Fe L lines, by a starburst component in the host galaxy cannot be ruled out with the present data.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：WILEY-V C H VERLAG GMBH  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：KLUWER ACADEMIC PUBL  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The ASCA results of the starburst galaxy M82 are presented. The X-rays in the 0.5-10 keV band exhibit a thin thermal spectrum with emission lines from highly ionized magnesium, silicon, and sulfur, as well as a hard tail extending to higher than 10 keV energy. The soft X-rays are spatially extended, while the hard X-rays show an unresolved point-like structure with possible a long-term flux variability. The flux ratio of the emission lines and the spatially extended structure in the low-energy band indicate that at least two-temperature thin thermal plasmas are present. The abundances of the oxygen, neon, magnesium, silicon, sulfur, and iron in the thin thermal plasmas are found to be significantly lower than the cosmic value. Neither type-Ia nor type-II supernova explosions can reproduce the observed abundance ratio. The origin of the unresolved hard X-rays is uncertain, but is probably an obscured low-luminosity AGN.

DOI： 10.1093/pasj/49.6.619

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We observed Stephan's Quintet, a compact group of galaxies, with the Japanese X-ray satellite ASCA. The ASCA observation has revealed that the X-ray emission consists of two components. One is a soft X-ray emission characterized by thin thermal model with kT = 0.76(-0.10)(+0.05) keV and a metal abundance of 0.08 +/- 0.04 solar. Since the soft X-rays are extended and the centroid is located at the region between NGC 7318 and NGC 7319, thin thermal emission originates from diffuse hot gas filling the Quintet. The total mass of hot gas is about 2 x 10(10)M(.), which is only 10% of the galaxy mass. The low metal abundance indicates that most of the hot gas consist of primordial gas. The binding mass is about 6 x 10(12)M(.). The baryonic fraction is about 10%. The other component is hard X-ray emission located at NGC 7319, a Seyfert 2 galaxy. The X-ray spectrum is well fitted by the absorbed-power law emission plus a line. The photon index is 0.8(-1.1)(+0.8), and the absorption column is about 10(23) cm(-2). The X-ray luminosity in the 2-10 keV band is about 1.7 x 10(42) erg s(-l). These characteristics are consistent with those of Seyfert 2 galaxies. We have revealed an obscured nucleus in NGC 7319. Our results well explain the flux of Ha and anisotropic radiation seen in the optical band.

DOI： 10.1093/pasj/49.4.445

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We have systematically investigated the Advanced Satellite for Cosmology ann Astrophysics (ASCA) spectra of 12 early-type galaxies. This paper presents the global spectral properties of these systems based on a larger sample than in any previous ASCA study. The X-ray spectra were uniformly fitted by a two-component model consisting of hard X-rays from thermal emission with a temperature of about 10 keV or from a power law with index 1.8, plus soft X-rays from a thin thermal plasma with temperature ranging from 0.3 to 1 keV. The X-ray luminosities of the hard component are found to be proportional to the blue-band luminosities, while those of the soft component show large scatter with no clear correlation. The metal abundances determined from the soft component are systematically lower than solar, with a mean value of about 0.3 solar. We examine the relationships between the temperature and volume emission measure and between the gas temperature and the stellar velocity dispersion. The volume emission measures for early-type galaxies plotted as a function of the gas temperature are well below the extrapolated line found in clusters of galaxies, indicating that early-type galaxies are relatively gas poor compared with galaxy clusters. The ratio of the stellar kinetic energy per unit mass to the thermal energy of the hot gas per unit mass (beta(spec)) is less than unity. We found no systematic relationship between X-ray properties and environment, suggesting that the interaction between interstellar matter and the intracluster medium is not strong.

DOI： 10.1086/304132

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We studied the proton damage effects of the X-ray CCD, and searched for a possible restoration technique in orbit. We measured the X-ray CCD performances after irradiation at energies of 2 and 9.5 MeV, and confirmed a clear degradation of the charge transfer efficiency (CTE) and the energy resolution. To restore the degraded CTE and energy resolution, we tried a charge injection technique, and found the improvement in the CTI (= 1 - CTE) and energy resolution to be 1/4 and 1/3, respectively. We also estimated the energy level of the deep trap, which causes a quantization of the dark current from the radiation-damaged pixels. The trap energy level was about 0.57 eV, or near to the center of forbidden band.

DOI： 10.1093/pasj/49.3.405

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We present results on the Seyfert 2 galaxy NGC 4388 in the Virgo cluster observed with ASCA during its performance verification (PV) phase. The 0.5-10 keV X-ray spectrum consists of multiple components: (1) a continuum component heavily absorbed by a column density N-H approximate to 4 x 10(23) cm(-2) above 3 keV; (2) a strong 6.4-keV line (equivalent width EW similar to 500 eV); (3) a weak flat continuum between 1 and 3 keV; and (4) excess soft X-ray emission below 1 keV. The detection of strong absorption for the hard X-ray component is firm evidence for an obscured active nucleus in this Seyfert 2 galaxy. The absorption-corrected X-ray luminosity is about 2 x 10(42) erg s(-1). This is the first time that the fluorescent iron K line has been detected in this object; the large EW is a common property of classical Seyfert 2 nuclei. The flat spectrum in the intermediate energy range may be a scattered continuum from the central source. The soft X-ray emission below 1 keV can be thermal emission from a temperature kT similar or equal to 0.5 keV, consistent with the spatially extended emission observed by ROSAT HRI. However, the low abundance (Z similar to 0.05 Z(circle dot)) and high mass flow rate required for the thermal model and an iron K line stronger than expected from the obscuring torus model are puzzling. An alternative consistent solution can be obtained if the central source was a hundred times more luminous over a thousand years ago. All the X-ray emission below 3 keV is then scattered radiation.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

The Japanese X-ray satellite ASCA observed NGC 1808, which is known to exhibit both Seyfert and starburst activities. In the soft X-ray band, ASCA detected emission lines from highly ionized Mg and Si, which confirmed the presence of a thin thermal plasma, due possibly to starburst activity. The thin thermal plasma consists of two temperature components of kT similar to 0.78 keV and kT similar to 0.35 keV. We found that the intrinsic absorption toward the 0.78 keV plasma is N-H similar to 7 x 10(21) cm(-2), which is greater than the galactic foreground value of 2.8x10(20) cm(-2) (Dickey; Lockman 1990, AAA 53.155.163). This result implies that most of the X-ray emission from this plasma comes from the central region. The absorption toward the 0.35 keV plasma, on the other hand. shows a low value compared to the galactic absorption. This indicates that the plasma is more extended like an X-ray halo. The metal abundance of about 1 solar value found in the thin thermal plasma is larger than that of the archetypical starburst galaxy M82. In addition to the thin hot plasma, ASCA detected a hard X-ray component from NGC 1808, with a luminosity of 2X10(40) erg s(-1) (0.5-10 keV band), obscured by an absorbing column of 1.0x10(22) cm(-2). The hard X-ray flux and spectrum may also be attributable to starburst activity. However, the hard X-rays exhibited a long-term variability from the Ginga and ASCA observations, suggesting the presence of a low-luminosity AGN in NGC 1808.

DOI： 10.1093/pasj/48.3.409

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We present the results of ASCA observations of the Seyfert galaxy Mkn 463. We find that the 1-10 keV X-ray spectrum consists of at least two components: soft and hard. We have found no evidence for a strong Fe-K fluorescent line (equivalent width &lt; 670 eV). The soft component dominates below 4 keV and has a steep slope; the 0.2-4 keV flux is consistent with that determined from Einstein observations. It would appear that this soft X-ray emission comes from a distinct thermal component. The hard component, which has been detected for the first time by ASCA, is found only above 4 keV with an apparent flat spectral slope. We argue that most of these hard X-rays are emitted directly from the nucleus of Mkn 463E, suffering a heavy absorption along our line of sight. For an assumed typical photon index of 1.7, the absorption column and intrinsic luminosity are estimated to be (1.8 +/- 0.4) x 10(23) cm(-2) and 1 x 10(43) erg s(-1). This hard X-ray luminosity is much less than that expected on the basis of Mkn 463E's optical and infrared properties.

DOI： 10.1093/pasj/48.3.389

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

We present analyses of two Ginga observations and two observations from the ROSAT database of NGC 7469, focusing on the spectral variability observed on timescales of days and longer. During the 3 day 1988 Ginya observation, the hardness ratio (8-21 keV/3.4-5.7 keV) increased significantly as the total flux decreased by 30%. As the spectrum is well fit by the reflection model and since the spectral variability dominates the higher energy band, this could be explained by either a variation in the power-law index or in the effective covering fraction of the reflecting material. This ambiguity is inherent in reflection modeling of Ginga spectra from moderate flux Seyfert 1 galaxies. Assuming that the power-law index did not change, we find that the reflected flux is consistent with being constant, suggesting that much of the reflecting material may be located more than 3 light-days from the continuum source with the molecular torus being a plausible site. This scenario is also supported by the report of a narrow rather than broad iron K alpha line in the ASCA data by Guainazzi et al. NGC 7469 was faint during the 1989 Ginga observation, but variability was observed with doubling timescale of 5 hr, and the spectrum was harder. A reflection component could not be constrained, and the change in the spectrum could be explained by an increase in neutral absorption.
The brighter of two ROSAT spectra was significantly softer, and in both spectra there was evidence of spectral complexity, as has been previously reported by Turner, George, & Mushotzky and Brandt et al. The spectrum could be fit by a variety of two-component models, including a warm absorber model, an ionized disk model, and a thermal model with single-component blackbody spectrum, but joint fitting of the 1988 average Ginya spectrum and the nonsimultaneous ROSAT spectra favored thermal models, as other models required an anomalously high reflection ratio. This model is supported by the observation of a soft excess component and the lack of ionized absorption edges in the ASCA spectrum by Guainazzi et al. The long-term spectral variability could be explained by relative variability between the power-law and soft excess component normalizations, perhaps implying that hard X-ray reprocessing in thermal material does not dominate on long timescales.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We present the Ginga and ASCA results for the narrow emission line galaxy NGC 2110. Using Ginga data we found a fast time-variability of a few hours, superimposed on a relatively constant X-ray flux. The X-ray spectrum was well fitted with an absorbed power-law plus iron K emission-line model, in which no significant reflection component was required. Using ASCA data we confirmed the previous detection of extra soft X-ray emission and a K-shell emission line from ''cold'' iron in the simple absorbed power-law spectrum. For the first time we detected a K-shell absorption edge of ''cold'' iron. This edge feature, combined with the Ginga results, indicates that the reflection process is not dominant in NGC 2110. We propose that these iron line and edge features are due to a partial covering material with N-H similar to 10(23) cm(-2), which presumably comprises ''hidden'' broad line region (BLR) clouds.

DOI： 10.1093/pasj/48.2.219

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OXFORD UNIV PRESS  

We present the ASCA results of spatially resolved X-ray spectra in the central regions of the Virgo cluster, near to the central elliptical galaxy M87 and 40' northwest of M87 (M87 NW). Since the spectra of the M87 region is complex, an adequate fit requires at least two thin thermal-plasma components. The temperatures of the hot and cool components are approximately 3.0 and 1.3 keV, respectively, and the temperature of these components are both nearly constant over the central 10' radius from the center of M87. The spectrum of M87 NW, on the other hand, can be well fitted by a single thin thermal-plasma model of similar to 2.7 keV temperature. The abundances of Fe, Si, and S rise towards the center of M87, though the ratios of Si/Fe and S/Si remain constant. We also found, contrary to the Einstein Observatory's results, that the abundance ratio of oxygen to iron (O/Fe) is smaller than the solar value.

DOI： 10.1093/pasj/48.2.201

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：BLACKWELL SCIENCE LTD  

We report the detection of a very broad iron K alpha emission line in the ASCA X-ray spectrum of the Seyfert 2 galaxy IRAS 18325 - 5926. The line is strong, with an equivalent width EW = 500-800 eV, and its profile is peaked at 6.9 keV and skewed down to 4 keV. The energy of the blue peak of the line is significantly higher than the rest-energy of 6.4 keV seen in many active galaxies, which is expected from an iron K alpha line arising in cold matter. If the breadth and shift of the line energy are caused by Doppler and relativistic effects in a cold accretion disc about a black hole, then the disc has an intermediate inclination, i = 40 degrees-50 degrees. A plausible interpretation for the large equivalent width is a supersolar abundance of iron; this also accounts for the lack of a significant reflection hump. The line profile can also be explained by emission from highly ionized matter very close to the central object. However, the lack of a deep iron K absorption edge in the Ginga spectrum is inconsistent with this interpretation.
We verify that fast X-ray variability on a time-scale of 10(4) s is common in this object, using ASCA and ROSAT observations which are partially simultaneous. A study of spectral variability using combined ASCA and ROSAT PSPC data reveals that the X-ray flux change occurred mainly above 1 keV, and suggests a stable, or at least less-variable, component below 1 keV. It should lie outside the nuclear obscuration region.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：OPTICAL SOC AMER  

The x-ray properties of multinested thin-foil mirror x-ray telescopes (XRT's) on board ASCA, the Advanced Satellite for Cosmology and Astrophysics, were fully evaluated with an x-ray pencil beam. Scanning over the telescope aperture of 35 cm in diameter with an x-ray pencil beam, we found the effective area of a set of XRT's to be 325, 200, and 113 cm(2) at energies of 1.5, 4.5, and 8.0 keV, respectively. We derive the point-spread functions (PSF's) of the XRT's by measuring the image profile at the focal plane with an x-ray CCD. The PSF is found to exhibit a sharp core concentrated within 30 arcsec and a broad wing extended to 3 arcmin in half-power diameter. We also evaluate the contribution of stray light, which is caused by the single reflection of x rays by primary or secondary mirrors and by the backside reflection of the mirrors. To obtain the characteristics of the XRT in the energy region of 0.5-10.0 keV, incorporated with the measurements at discrete energies, we develop a ray-tracing method with the telescope design parameter, the PSF, and optical constants. In particular, we obtain the optical constants around the gold-atom M shell (Au-IM) absorption-edge energies by measuring the reflectivity of our mirror sample, with monochromatized x-rays in the energy range of 2.0-3.5 keV from synchrotron radiation. Taking into account the PSF's and optical constants, we find that our ray-tracing program can reproduce all these XRT performances. (C) 1995 Optical Society America.

DOI： 10.1364/AO.34.004848

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：AMER INST PHYSICS  

We report x-ray and optical spectroscopic observations of an IRAS-selected Seyfert 2 galaxy IRAS 18325-5926. The first x-ray observation of this object was made using the Ginga LAG. The x-ray source is found to be highly variable on time scales of 10(3)-10(4) s, similar to those of Seyfert 1 nuclei. The x-ray spectrum is well described by power-law continuum with a photon-index Gamma similar or equal to 2.2 modified by photoelectric absorption intrinsic to the source with N-H similar or equal to 1.4x10(22) cm(-2) and a broad (sigma approximate to 0.6 keV) iron K line. The absorption corrected x-ray luminosity in the 2-10 keV band is L(X)=5.4x10(43)h(50)(-2) ergs s(-1). We obtained new optical spectra in red and blue bands, which show the strong emission lines of typical Seyfert 2s with a heavy reddening (A(V)=3.5 mag). A blue asymmetry is obvious in some strong emission Lines and we can resolve narrow (FWHM similar or equal to 450 kms(-1)) and slightly blueshifted (similar or equal to 160 km s(-1)) broad (FWHM similar or equal to 1200 km s(-1)) components. The optical classification of Seyfert 2s can be explained in terms of nuclear obscuration which may occur in the form of a ''global'' covering rather than in the form of a torus inferred from the unified model, since the extinction derived from optical and x-ray data are comparable. This fact suggests that the hypothesis in which the classification between Seyfert 1's and 2's depends on the orientation is not complete, and a global obscuration is likely to dominate the dusty IRAS galaxies with Seyfert 2 characteristics. (C) 1995 American Astronomical Society.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：AIP PRESS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

The ASCA instrument uses identical conical foil X-ray mirrors for its four telescopes. One of the major advantages of ASCA's telescopes is the first time ever use of X-ray imaging over a broad energy band and high throughput for conducting astronomical spectroscopy. Nested thin foil reflectors make possible a large effective area up to 10 keV, even under the tight weight restriction of the ASCA spacecraft. The expected characteristics of the ASCA mirrors are summarized based on ray tracings and pre-flight calibrations. The total effective area of four telescopes at 1 and 7 keV are approximately 1200 and 600 cm2, respectively. The image size (half power diameter : HPD) is about 3'. The field of view is 24' and 16' FWHM for 1 and 7 keV, respectively. Observations of several X-ray sources from space during the performance verification phase have confirmed those performances as well as the alignment of the optical systems.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We present our analysis of ASCA PV phase observations of the elliptical galaxies NGC 1404 and NGC 4374 (M84). The average metallicities in the hot gas derived from the SIS spectra are exceptionally low, Z similar to 0.15 solar, while the temperatures are ''typical,'' kT similar to 0.75 keV. We also place upper limits on intrinsic column densities. The low abundances lend support to the theory of Fe enrichment of intracluster media by protogalactic Type II supernova-driven winds and raise the possibility of a fundamental connection between baryon fraction, dissipation, and abundances in elliptical galaxies.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

Five bright elliptical galaxies in the Virgo Cluster, NGC 4365, NGC 4374 (M84), NGC 4406 (M86), NGC 4472 (M49), and NGC 4636, were observed with ASCA. In addition to the extended thermal X-ray emission of temperature kT similar to 1 keV, harder X-rays with color temperature kT greater than or equal to 2 keV were detected from all of them. The 2-10 keV luminosities of this hard component for the five galaxies, integrated within 5', are distributed within a relatively narrow range of (1-4) x 10(40) ergs s(-1). The hard X-ray component is primarily attributed to the integrated emission from discrete X-ray sources. In NGC 4406 and NGC 4374 the data indicate that the hard component is contributed additionally by foreground/background emission from the hot intracluster medium (ICM) of the Virgo Cluster. The hard component of NGC 4472 seems also contributed by the Virgo ICM emission, but in this case there is evidence that the ICM brightness is locally enhanced within similar to 10' of NGC 4472.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We present our analysis of ASCA PV phase observation of the elliptical galaxy NGC 4636. SIS spectra in six concentric annuli centered on NGC 4636 are used to derive temperature, metallicity, and column density profiles for the hot interstellar medium. Outside of the central 3' the temperature is roughly constant at similar to 0.85 keV, while the metallicity decreases from &gt;0.36 solar at the center to &lt;0.12 solar at R similar to 9'. The implications of this gradient for elliptical galaxy formation and the enrichment of intracluster gas are discussed. We derive a detailed mass profile consistent with the stellar velocity dispersion and with ROSAT PSPC and ASCA SIS X-ray temperature profiles. We find that NGC 4636 becomes dark matter dominated at roughly the de Vaucouleurs radius, and, at r similar to 100 kpc, the ratio of dark to luminous matter density is similar to 80 and M./L. approximate to 150. Evidence for the presence of a cooling flow is also discussed.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：IOP PUBLISHING LTD  

The Seyfert 1 galaxy NGC 6814 was observed using the Japanese X-ray astronomy satellite Ginga in 1990 April and October. The rapid variability characteristically associated with this source was reconfirmed. Specifically, three dips were found in the April observation in which the flux dropped to nearly zero in similar to 300 s. The doubling timescale was similar to 50 s. A similar but separated drop and rise in flux was observed in the October data, different in that the flux did not decrease completely to zero.
A detailed analysis of the data around the structures of most rapid variability found spectral variability and lags in flux between different energy bands. Lags were on the order of a few to tens of seconds for the April data, and on the order of tens to a couple of hundred seconds for the October data. The sense of the lags was such that during flux decreases the hard flux lagged, while during flux increases the soft flux lagged. Associated significant apparent hardening of the spectrum at low flux was observed in the April data. Apparent hardening of the spectrum also occurred in the October flux decrease, to a photon index of Gamma = 0.85; however, the spectrum softened at lowest flux to the index of the predecrease level, Gamma = 1.54. In the April dips, the line flux was found to decrease significantly. A marginal decrease in line flux was also observed in the October data. The variability of the line flux reconfirmed the result of Kunieda et al. (1990), who found that the line producton region must be within similar to 300 light-seconds from the source.
To explain the observational results, a variable-absorption model was proposed, in which the column density was assumed to vary as a function of time. The time dependence of the column was determined in two ways. First, the functional dependence was assumed to be exponential, and model parameters were derived by fitting explicitly to the lag data obtained from the October observation. Second, a partial-covering spectral model was assumed, and the column density implied by the change in flux was found for both observations. The exponential folding time of the column density implied during the October flux decrease could be reliably determined to be about 100 s. The spectral variability could be qualitatively explained by the variable-absorption model, since superposition of continuously variable columns can result in an apparent hardening of the spectrum when measured by moderate-resolution instruments. The differences between the April and October observations could be explained if the two model parameters, the fraction of unabsorbed flux and the gradient with respect to time of the column density, were adjusted. Other physical processes, including intrinsic spectral changes and warm absorber models, which could account for the fastest variability, could be ruled out by the results of the data analysis. A primary constraint found for geometrical models is that the material which is doing the absorption must have relatively low ionization (xi &lt; 100). This result leads to severe constraints on a general orbiting cloud model, requiring high densities (n similar to 10(16) cm(-3)) and sheetlike geometry.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

With the high sensitivity and spectral resolution of the ASCA satellite, we have discovered strong emission lines from the H-like and/or He-like ions of Ne, Mg, Si, and S as well as Fe L and confirmed the complex structure of Fe K line emission in the Seyfert II galaxy NGC 1068. The continuum emission above 3 keV exhibits rather flat shape with no evidence of low energy absorption. The overall X-ray spectrum can be well explained with a model involving starburst activity plus an obscured active galactic nucleus.

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Language：English   Publisher：ASTRONOMICAL SOC JAPAN  

We report preliminary results of an ASCA observation of the Seyfert 2 galaxy Mkn 3. Comparison with previous Ginga and BBXRT observations shows that the observed hard X-ray luminosity above 4 keV decreased by a factor of approximately 3 (intrinsic luminosity by almost a factor of 6) in a period of approximately 3.6 yr. On the other hand, the soft luminosity has not varied significantly in approximately 13 yr, lending support to the extended nature of the soft emission, perhaps dominated by scattering of the nuclear X-rays. ASCA resolves the Fe K line emission into at least two components for the first time. The dominant component at 6.4 keV has an equivalent width of approximately 860 eV and FWHM approximately 10(4) km s-1, while the second component has an equivalent width of approximately 190 eV and appears to be narrower than the first. The total intensity of the Fe K emission decreased by factor of over 3 in response to the decrease in the continuum level, implying that a substantial part of the dominant Fe K emission must originate in a region smaller than that responsible for the soft emission. The variability provides direct evidence that the hard X-ray continuum and Fe K line in this Seyfert 2 are being observed directly through the nuclear obscuring material, not in scattered light.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

We report ASCA 0.3-10 keV X-ray observations of three early type galaxies, NGC 4472, NGC 4406, and NGC 4636. The extended emission in these galaxies is well described by thin thermal emission from hot gas. The gas temperature is 0.92 +/- 0.02 keV for NGC 4472, 0.79 +/- 0.01 keV for NGC 4406, and 0.73 +/- 0.02 keV for NGC 4636. The metal abundance for NGC 4472, NGC 4406, and NGC 4636 are, under the assumption of solar ratios, 0.63 +/- 0.15, 0.45 +/- 0.10, and 0.38 +/- 0.07, respectively. Detailed analysis has allowed determination of the abundances of oxygen, silicon, sulfur, and iron. The observed abundances axe consistent with the solar ratios. For NGC 4472 and NGC 4406 we also determined the mean temperature of the gas producing the Si lines from the ratio of the Si H to He-like lines and find it to be consistent with the continuum temperature. The X-ray temperature is in good agreement with the observed optical velocity dispersion, stellar density profile, and gas density profile. Our data indicates that the supernova rate should be less than one fifth of the nominal rate in early type galaxies. We derive the mass of these systems within fixed angular scales and find that M/L &gt; 40, confirming that elliptical galaxies are dark matter dominated at large radii.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：JAPAN SOC APPLIED PHYSICS  

A 30-m-long X-ray beam line has been built at the Institute of Space and Astronautical Science (ISAS) to evaluate the performance of X-ray optical instruments for space programs, in particular for the X-ray telescope on-board the Astro-D (Asca) satellite. This beam line consists of an X-ray generator, a 30-m-long vacuum duct, and measuring chambers. Strong and stable X-ray pencil beams from Al, Ti, Cu, Mo and W targets are available with the parallelism of several arcs [full width at half maximum (FWHM)]. Three kinds of detectors are prepared: a conventional gas proportional counter equipped with a thin plastic window, a one-dimensional position-sensitive proportional counter with a Be window, and a charge-coupled device (CCD) modified for X-ray measurements. At the present compact beam line, instead of giant systems of hundreds of meters, the combination of a strong X-ray (0.2-10 keV) pencil beam and translation stages enables us to examine the entire aperture of large X-ray optical instruments of up to 40 cmphi and 1 m in length.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We have observed the infrared galaxy NGC 4945 using the Japanese X-ray astronomy satellite, Ginga. The X-ray spectrum is found to be composed of three components: hard X-ray emission which is heavily absorbed by cold material with column density of about 10(24.7) cm-2; a soft X-ray component seen in the 2-10 keV band; and an iron emission line, The hard component exhibits a power-law spectrum with photon index of about 1.7. The mean X-ray luminosity in the 2-20 keV band, after correction for absorption is 3 x 10(42) ergs s-1 with significant intensity variation on a time scale of several hours. These results are thought to be evidence for an AGN (active galactic nucleus) in the galaxy. The X-ray spectrum of the soft component can be fitted with a power-law model having nearly the same photon index, but the luminosity is only 3% that of the hard component. The soft component shows no time variability. The energy of the iron line is found to be 6.5 +/- 0.1 keV, and the equivalent width is 1.5 +/- 0.3 keV. The X-ray spectrum is interpreted to be composed of the X-ray emission from a hidden Seyfert nucleus behind an obscuring torus, the scattered continuum radiation, and a fluorescence line emission from ionized iron in the scattering medium. Thus NGC 4945 is the first example of an active galaxy which exhibits both the obscuring and scattering picture of the type 2 AGN.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

Simultaneous X-ray and UV observations of the Seyfert 1 galaxy NGC 3516 were carried out to investigate the connection between the variable X-ray and ultraviolet absorption features. Over a 2 week period, X-ray spectra were obtained with Ginga, simultaneously with UV spectra from IUE. The X-ray spectrum was complex and could be fitted satisfactorily with a warm absorber model, a partial covering model, or a cold reflector model, in addition to an overlying column density of N(H) is similar to 4 x 10(22) cm-2. The X-ray absorption remained unchanged (in all the spectral models), while the spectral index alpha changed significantly. The Fe Kalpha line was generally found to be strong (EW is similar to 250-400 eV). The UV spectra displayed a significant variation in the continuum flux, while the absorption features in the C IV lambda1550, N V lambda1240, and Si IV lambda1400 lines stayed constant. A common origin of the UV and X-ray absorption could not be established due to the absence of variability in either the X-ray or the UV absorption. A lower limit on the column densities of the UV absorber is approximately 2 x 10(19) cm-2. Assuming that the variability in the C IV lambda1550 absorption (as detected in the archival data) is due to changes in the ionization level, the UV absorbers should be located closer than 9 pc from the ionizing source for log N(H) is similar to 20, and at smaller distances for higher column densities. Based on estimates of the absorbing properties of a low-luminosity AGN in the framework of broad absorption line (BAL) theories, we suggest that NGC 3516 is consistent with a low-luminosity equivalent of a BAL QSO. Finally, we discuss the likely location of the UV absorbers in optically thin clouds in the broad line region. A common origin of the UV and X-ray absorption in such clouds is probably ruled out.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：PERGAMON PRESS LTD  

We observed twenty-eight Seyfert 2 galaxies with the Japanese X-ray satellite, Ginga, and found Seyfert 2 galaxies, in general, have the X-ray spectral characteristics of obscured Seyfert 1 nuclei. This result agrees with the predictions from Unified Seyfert model proposed by Antonucci and Miller/1/. However, among the observed Seyfert 2 galaxies, there are a few galaxies with no evidence of an obscuration, contrary to the general predictions of the unified model. We note that type 2 AGN will contribute to the Cosmic Diffuse X-ray Background, if the unified Seyfert model can be extended to the far distant AGN such as quasars.

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Language：English   Publisher：ASTRONOMICAL SOC JAPAN  

HE 1029-1401 (z = 0.086) is a recently discovered southern bright quasar (V = 13.86; M(V) = -25.1), and is one of the most luminous QSOs with a low redshift (z &lt; 0.1) in the optical and UV wavelengths. We report here on possible X-ray detection from HE 1029-1401 by the Ginga satellite. This new QSO is found in the error regions of an X-ray source observed with the HEAO-1 and Ginga satellite. The X-ray spectrum shows a flat power-law (alpha(E) approximately 0.5) in the high-energy band, and excess emission in soft X-rays, which have been often observed in many QSOs. From the X-ray light curve, we find a flux variation on a time scale with an order of half a day. This time variability is fairly rapid, compared to known AGNs with a similar X-ray luminosity.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

We report the first detection of hard X-rays (above 2 keV), from the narrow-line radio galaxy (NLRG) IC 5063. The hard X-ray spectrum is described by a power-law photon index of 1.5 with a large absorption corresponding to the N(H) value of 2 X 10(23) H cm-2. The X-ray luminosity (2-20 keV band) after the correction of the absorption is 2.5 x 10(43) ergs s-1. Since the X-ray luminosity and spectral index are in the range found for Seyfert 1's and broad-line radio galaxies (BLRG), we conclude that IC 5063 has an intrinsic BLRG type nucleus hidden behind a high gas column. There is a hint of X-ray flux variations with time scales between 10(3) s and 10 hr which, if confirmed, would further support that the hard X-rays are the direct beam from a compact nucleus penetrating the high gas column.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

The high-luminosity radio-quiet quasar E1821 + 643 has been observed with Ginga. The 2-10 keV spectrum has a power-law energy index, alpha, of 0.9 and the flux is (2.0 +/- 0.3) x 10(-11) ergs cm-2 s-1. The absorption is consistent with the Galactic value of N(H) = 4 x 10(20) cm-2. The spectrum shows strong evidence for the presence of a redshifted iron K emission line of center energy 5.1 +/- 0.2 keV (6.6 +/- 0.3 keV, redshift corrected; z = 0.297), and an observed equivalent width of 210 +/- 80 eV. There is evidence that E1821 + 643 may be embedded within a cluster of galaxies which could contribute part of the observed line. The equivalent width (EW) ascribed to the quasar cannot, therefore, be accurately determined, but lies in the range 60 eV less-than-or-similar-to EW less-than-or-similar-to 380 eV (after redshift correction). The upper limit to the intrinsic absorption of 1 x 10(22) cm-2 rules out production of the line by fluorescence in cold material in the line of sight, but several other possible origins for the line are not constrained by our data. The detection of a redshifted iron line opens the possibility that iron emission lines may be a common feature in the X-ray spectra of quasars. This would have a considerable impact on the study of quasars by future X-ray missions.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：EDP SCIENCES S A  

A long Ginga observation of the broad line radio galaxy 3C 382 shows low amplitude X-ray variability with a characteristic time scale of 2 days. No evidence for variability with rms amplitudes larger than 4% on shorter time scales is found. The X-ray flux was 50% below the minimum of 30 previous detections. The variability amplitude as deduced from this and previous observations increases up to at least a time scale of one year. Identifying the minimum and maximum variability time scales with the thermal and viscosity time scale in an accretion disk around a massive black hole, a central mass of approximately 10(8) M. and an accretion rate of approximately 0.1 M. yr-1 results. These parameters are also consistent with the UV continuum spectrum.
We report for the first time an Fe-fluorescence line in 3C 382. The line energy reduced to the rest frame of 3C 382 is 6.52 +/- 0.27 keV, consistent both with cool or hot material. The line equivalent width of 280 eV is very high. This may be either related to the probably large inclination of the accretion disk in 3C 382 or due to time delay effects in combination with the low continuum flux.
The soft excess below 2 keV varies differently from the main power law, but with a similar time scale. Its spectral shape is poorly determined but its temperature of approximately 5 x 10(6) K is much higher than found in previous EXOSAT observations, while its bolometric luminosity is only approximately 10% of the 2-10 keV luminosity. If this difference with EXOSAT is related to the low flux during the present Ginga observation, a strong anticorrelation between temperature and flux of the soft X-ray excess in 3C 382 is implied.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

We observed 16 Seyfert galaxies, including 9 Seyfert 2 galaxies, with the Ginga satellite. Thirteen of the Seyfert galaxies in our sample have been detected, and the iron line and K-edge structure for these galaxies investigated. Twelve of the thirteen detected galaxies also have a detected iron line. The equivalent width of a Seyfert 1 galaxy is distributed around a mean value of about 173 eV, with a standard deviation of about 40 eV; that for a Seyfert 2 galaxy is scattered from &lt; 80 eV to 1300 eV. Most of the detected galaxies show an absorption feature at the energy of the iron K-edge. The iron column density determined from the iron K-edge structure ranges from &lt; 10(17.5) cm-2 to 2 x 10(19) cm-2. Using a Monte Carlo simulation, we found that isotropic X-ray emission within a uniformly distributed gas cannot explain the observed result. The overall distribution of the iron line and the K-edge intensity for all of the galaxies in our sample could be reproduced by using an accretion torus model with a single parameter: the viewing angle to the active galactic nucleus within an accretion torus.

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：EDITIONS FRONTIERES  

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Language：English   Publisher：ASTRONOMICAL SOC JAPAN  

We discovered an obscured nucleus in Seyfert 2 galaxy NGC 4507 with the Ginga satellite. The 2-10 keV X-ray luminosity is 3.2 x 10(43) erg s-1, and the continuum radiation is well described by a power law model with a photon index of 1.34(-0.25)+0.28. The column density of the obscuring matter is (4.9 +/- 0.7) x 10(23) cm-2, which is sufficiently thick to hide the broad-line region and the nucleus. An iron line with equivalent width of 420(-110)+100 eV has also been detected in the X-ray spectrum. In order to explain the large equivalent width, a large covering factor for the matter around the nucleus is needed. The obscuration can be naturally explained in terms of a torus in the unified Seyfert model.

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MACMILLAN MAGAZINES LTD  

DOI： 10.1038/346544a0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MACMILLAN MAGAZINES LTD  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：KLUWER ACADEMIC PUBL  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：UNIV CHICAGO PRESS  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MACMILLAN MAGAZINES LTD  

DOI： 10.1038/340289a0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：MACMILLAN MAGAZINES LTD  

DOI： 10.1038/339603a0

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

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Language：English   Publishing type：Research paper (international conference proceedings)   Publisher：EUROPEAN SPACE AGENCY  

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Language：English   Publishing type：Research paper (scientific journal)   Publisher：ASTRONOMICAL SOC JAPAN  

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J-GLOBAL

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Language：Japanese   Publisher：宇宙航空研究開発機構宇宙科学研究所(JAXA)(ISAS)  

大気球シンポジウム 平成30年度（2018年11月1-2日. 宇宙航空研究開発機構宇宙科学研究所 (JAXA)(ISAS)）, 相模原市, 神奈川県著者人数: 37名資料番号: SA6000128005レポート番号: isas18-sbs-005

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Language：Japanese  

J-GLOBAL

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Language：Japanese  

J-GLOBAL

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

FORCE is a 1.2 tonnes small mission dedicated for wide-band fine-imaging x-ray observation. It covers from 1 to 80 keV with a good angular resolution of 15′′ half-power-diameter. It is proposed to be launched around mid2020s and designed to reach a limiting sensitivity as good as FX(10 - 40 keV) = 3 × 10-15 erg cm-2 s-1 keV-1 within 1 Ms. This number is one order of magnitude better than current best one. With its high-sensitivity wideband coverage, FORCE will probe the new science field of "missing BHs", searching for families of black holes of which populations and evolutions are not well known. Other point-source and diffuse-source sciences are also considered. FORCE will also provide the "hard x-ray coverage" to forthcoming large soft x-ray observatories.

DOI： 10.1117/12.2309344

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

We fabricated X-ray mirrors from carbon-fiber-reinforced-plastic (CFRP) with a tightly nested design for X-ray satellites. The mirror shape is Wolter type-I quadrant shell geometry with a diameter of 200 mm and a focal length of 12 m. The mirror substrates were successfully formed with a rms error of about 1 μm. Through a replication process, a smooth surface was obtained on the CFRP substrate. We are developing a positioning method of thin mirrors in a telescope housing. It is found that a piezo-linear motor is very useful to adjust the mirror position with accuracy of sub μm. The CFRP mirrors were evaluated by using 20 keV X-ray pencil beam at BL20B2 in SPring-8 synchrotron radiation facility. The HPD of the mirrors was estimated to be about 2.3 arc-minutes. The spread of X-ray image would be caused by small waviness on the mirror surface after replication.

DOI： 10.1117/12.2312037

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We have proposed a new type of X-ray interferometer called Multi Image X-ray Interferometer Module (MIXIM) consisting simply of a grating and an X-ray spectral imaging detector. The baseline concept of MIXIM is a slit camera to obtain the profile of X-ray sources, but aim to get a sub-arcsecond resolution. For that purpose, to avoid blurring of the image by diffraction is a key, and we select X-ray events of which energy satisfies the interferometric condition called Talbot effect. Stacking the images (X-ray interferometric fringes) with the period of the grating is another point of the method, which provides the self image of a grating slit convolved with the profile of the X-ray source. We started an experiment with a micro focus X-ray source, 4.8 μm pitch grating, and an SOI type X-ray detector XRPIX2b with a pixel size of 30 μm. The stacked self image was obtained with a magnification factor of 4.4. We, however, need finer positional resolution for the detector to obtain the self image to a parallel beam, for which the magnification factor must be 1. We thus focused on small pixel size CMOS sensors developed for visible light. We irradiated X-rays to one of such CMOS sensors GSENSE5130 with a pixel size of 4.25 μm, and found enough capability to detect X-rays, i.e., FWHM of 207 eV at 5.9 keV at room temperature. We then employed this sensor and performed an experiment at a 200 m beam line of BL20B2 in the synchrotron facility SPring8. Using a grating with a pitch of 4.8 μm and an opening fraction of f=0.5, we obtained the self image of the grating at the detector distance from the grating of 23 cm and 46 cm and the X-ray energy of 12.4 keV. We also performed an experiment using a 9.6 μm f = 0.2 grating with a detector-grating distance of 92 cm, and obtained higher contrast image of the grating. Note that the slit width of 2.4 μm at 46 cm corresponds to 1.1′′, while that of 1.9 μm at 92 cm does 0.43′′. We suggest several format of possible MIXIM missions, including MIXIM-S for very small satellite of 50cm size, MIXIM-P for parasite use of nominal X-ray observatory employing grazing X-ray telescopes with a focal length of 10 m, and MIXIM-Z in which the grating-detector distance of 100 m is acquired by formation flight or free fryers to yield 0.01" level resolution.

DOI： 10.1117/12.2314181

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

The ASTRO-H mission was designed and developed through an international collaboration of JAXA, NASA, ESA, and the CSA. It was successfully launched on February 17, 2016, and then named Hitomi. During the in-orbit verification phase, the on-board observational instruments functioned as expected. The intricate coolant and refrigeration systems for soft X-ray spectrometer (SXS, a quantum micro-calorimeter) and soft X-ray imager (SXI, an X-ray CCD) also functioned as expected. However, on March 26, 2016, operations were prematurely terminated by a series of abnormal events and mishaps triggered by the attitude control system. These errors led to a fatal event: the loss of the solar panels on the Hitomi mission. The X-ray Astronomy Recovery Mission (or, XARM) is proposed to regain the key scientific advances anticipated by the international collaboration behind Hitomi. XARM will recover this science in the shortest time possible by focusing on one of the main science goals of Hitomi, "Resolving astrophysical problems by precise high-resolution X-ray spectroscopy".(1) This decision was reached after evaluating the performance of the instruments aboard Hitomi and the mission's initial scientific results, and considering the landscape of planned international X-ray astrophysics missions in 2020's and 2030's.Hitomi opened the door to high-resolution spectroscopy in the X-ray universe. It revealed a number of discrepancies between new observational results and prior theoretical predictions. Yet, the resolution pioneered by Hitomi is also the key to answering these and other fundamental questions. The high spectral resolution realized by XARM will not offer mere refinements; rather, it will enable qualitative leaps in astrophysics and plasma physics. XARM has therefore been given a broad scientific charge: "Revealing material circulation and energy transfer in cosmic plasmas and elucidating evolution of cosmic structures and objects". To fulfill this charge, four categories of science objectives that were defined for Hitomi will also be pursued by XARM; these include (1) Structure formation of the Universe and evolution of clusters of galaxies; (2) Circulation history of baryonic matters in the Universe; (3) Transport and circulation of energy in the Universe; (4) New science with unprecedented high resolution X-ray spectroscopy. In order to achieve these scientific objectives, XARM will carry a 6 x 6 pixelized X-ray micro-calorimeter on the focal plane of an X-ray mirror assembly, and an aligned X-ray CCD camera covering the same energy band and a wider field of view. This paper introduces the science objectives, mission concept, and observing plan of XARM.

DOI： 10.1117/12.2309455

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Language：Japanese  

J-GLOBAL

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

The Focusing On Relativistic universe and Cosmic Evolution (FORCE) mission is proposed as a future Japan-lead X-ray observatory to be launched in the mid 2020s. FORCE is a successor of Hitomi, focusing on the braodband X-ray imaging spectroscopy in 1–80 keV with a significantly higher angular resolution of < 15′′ in half-power diameter. The sensitivity above 10 keV will be 10 times higher than that of any previous hard X-ray missions with simultaneous soft X-ray coverage. The satellite is planned to be launched by the Epsilon vehicle by ISAS/JAXA. In the current design concept, FORCE is equipped with three identical pairs of supermirrors and wideband X-ray detectors. The focal length of the mirrors is 10 m. The silicon mirror with multi-layer coating is our primary choice of optics to achieve a good angular resolution for the wide energy band while maintaining a light weight. The detector is a hybrid of a SOI-CMOS silicon-pixel detector and a CdTe detector responsible for the softer and harder energy bands, respectively. It is basically a descendant of the hard X-ray imager onboard Hitomi with its soft-band detector replaced with the SOI-CMOS. The primary scientific objective of the FORCE mission is to trace the cosmic formation history by searching for “missing black holes” in the entire range of the mass spectrum of BHs: “buried” supermassive black holes (SMBHs) (> 104 M), intermediate-mass black holes (102–104 M), and “orphan” stellar-mass black holes (< 102 M). Also, investigation of the nature of relativistic particles at various astrophysical shocks is in our scope, with high-angular-resolution X-ray observations with the broadband coverage. FORCE will open a new era in these fields.

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Language：Japanese   Publisher：Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)  

17th Space Science Symposium (January 5-6, 2017. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency(JAXA)(ISAS)Sagamihara Campus), Sagamihara, Kanagawa Japan

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

The Japanese X-ray Astronomy Satellite, Hitomi (ASTRO-H) carried two hard X-ray telescopes (HXT), covering the energy band from 5 keV to 80 keV. In the initial functional verification phase of the onboard instruments, G21.5-0.9 and Crab nebula were observed with HXT. The data of G21.5-0.9 observation indicated that the hard X-ray imaging system worked well. Detail calibration of the Hitomi HXTs was performed with the observation data of Crab nebula. We extracted X-ray images of the Crab pulsar excluding the nebular emission, and continued that the imaging perfounance in orbit was satisfied with the requirement of the HXT. The 8-80 keV Crab spectrum was well fitted with a power-law model with the absorbed column of N-H=3 x 10(21) cm(-2). The estimated photon index of 2.122 0.003 was consistent with previous results of Crab observation, while the observed 2-10 keV flux of 2.3x10-8 erg s(-1) cm(-2) was slightly larger than the previous observation. We note that there was discrepancy between the simulated and the measured effective area on ground. Thus, we introduced a fudge factor to reproduce the effective area obtained in the ground calibration. The fudge factor of HXTs are included in the latest calibration database of Hitomi.

DOI： 10.1117/12.2272844

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Language：Japanese   Publisher：The Physical Society of Japan  

&lt;p&gt;NGHXTあらため、FORCE衛星は1-80 keVの広帯域X線を高感度で撮像分光し、まだ見ぬ隠されたブラックホールや超新星残骸のフィラメントでの粒子加速の探査を目指している。2016年に変更した計画の内容、検出器および望遠鏡の開発状況、およびサイエンス検討の進捗を報告する。&lt;/p&gt;

DOI： 10.11316/jpsgaiyo.72.1.0_508

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© 2016 SPIE. We are developing an X-ray mirror using the CFRP as substrate in order to improve the angular resolution of tightlynested type X-ray telescope on board future X-ray satellites. We have fabricated Wolter-I designed monolithic CFRP mirrors and made improvements in the fabrication process. In the updated CFRP mirror, the half-power width of the reflection image by optical measurement was 0.8 arc-minutes on average. The measurement of the characterization of the updated CFRP mirrors at ISAS X-ray beam-line was performed in December 2015, and confirmed that the imaging quality of the CFRP mirror changed with increasing duration in vacuum chamber. We also present a current status of development of more intricate-structure CFRP substrate such as four-stage X-ray optics.

DOI： 10.1117/12.2232650

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© 2016 SPIE. The Japanese X-ray Astronomy Satellite, Hitomi (ASTRO-H) carries hard X-ray imaging system, covering the energy band from 5 keV to 80 keV. The hard X-ray imaging system consists of two hard X-ray telescopes (HXT) and the focal plane detectors (HXI). The HXT employs tightly-nested, conically-approximated thin foil Wolter-I optics. The mirror surfaces of HXT were coated with Pt/C depth-graded multilayers. We carried out ground calibrations of HXTs at the synchrotron radiation facility SPring-8/BL20B2 Japan, and found that total effective area of two HXTs was about 350 cm2 at 30 keV, and the half power diameter of HXT was about 1.'9. After the launch of Hitomi, Hitomi observed several targets during the initial functional verification of the onboard instruments. The Hitomi software and calibration team (SCT) provided the Hitomi's data of G21.5-0.9, a pulsar wind nebula, to the hardware team for the purpose of the instrument calibration. Through the analysis of the in-flight data, we have confirmed that the X-ray performance of HXTs in orbit was consistent with that obtained by the ground calibrations.

DOI： 10.1117/12.2231258

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© 2016 SPIE. The Hitomi (ASTRO-H) mission is the sixth Japanese X-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. After a successful launch on 2016 February 17, the spacecraft lost its function on 2016 March 26, but the commissioning phase for about a month provided valuable information on the on-board instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month.

DOI： 10.1117/12.2232379

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We are proposing FORCE (Focusing On Relativistic universe and Cosmic Evolution) as a future Japan-lead Xray observatory to be launched in the mid 2020s. Hitomi (ASTRO-H) possesses a suite of sensitive instruments enabling the highest energy-resolution spectroscopy in soft X-ray band, a broadband X-ray imaging spectroscopy in soft and hard X-ray bands, and further high energy coverage up to soft gamma-ray band. FORCE is the direct successor to the broadband X-ray imaging spectroscopy aspect of Hitomi (ASTRO-H) with significantly higher angular resolution. The current design of FORCE defines energy band pass of 1-80 keV with angular resolution of &lt; 15'' in half-power diameter, achieving a 10 times higher sensitivity above 10 keV compared to any previous missions with simultaneous soft X-ray coverage. Our primary scientific objective is to trace the cosmic formation history by searching for "missing black holes" in various mass-scales: "buried supermassive black holes (SMBHs)" (&gt; 10(4) M-circle dot) residing in the center of galaxies in a cosmological distance, "intermediate-mass black holes" (10(2)-10(4) M-circle dot) acting as the possible seeds from which SMBHs grow, and "orphan stellar-mass black holes" (&lt; 10(2) M-circle dot) without companion in our Galaxy. In addition to these missing BHs, hunting for the nature of relativistic particles at various astrophysical shocks is also in our scope, utilizing the broadband X-ray coverage with high angular-resolution. FORCE are going to open a new era in these fields. The satellite is proposed to be launched with the Epsilon vehicle that is a Japanese current solid-fuel rocket. FORCE carries three identical pairs of Super-mirror and wide-band X-ray detector. The focal length is currently planned to be 10 m. The silicon mirror with multi-layer coating is our primary choice to achieve lightweight, good angular optics. The detector is a descendant of hard X-ray imager onboard Hitomi (ASTRO-H) replacing its silicon strip detector with SOI-CMOS silicon pixel detector, allowing an extension of the low energy threshold down to 1 keV or even less.

DOI： 10.1117/12.2231262

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

© 2016 SPIE. A ray-trace simulation code for the Hard X-ray Telescope (HXT) on board the Hitomi (ASTRO-H) satellite is being developed. The half power diameter and effective area simulated based on the code are consistent with ground measurements within 10%. The HXT observed the pulsar wind nebula G21.5-0.9 for 105 ksec. We confirmed that the encircled energy function and the half power diameter obtained from the data are consistent with the ground measurements.

DOI： 10.1117/12.2232135

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

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J-GLOBAL

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.70.1.0_477

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Language：Japanese   Publisher：The Physical Society of Japan  

DOI： 10.11316/jpsgaiyo.70.1.0_478

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Language：English   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We are developing an X-ray mirror using the carbon fiber reinforced plastic (CFRP) as a substrate in order to improve the angular resolution of tightly-nested thin-foil Wolter-I X-ray mirrors. We found that curing of the epoxy used in the replication process at the room temperature is effective to suppress the print through. We were able to make mirrors whose shape accuracy is 3 5 pm. Characterization at the synchrotron facility SPring-8 using the X-ray pencil beam of 20 keV showed that the angular resolution was 3 - 5 arcmin as a whole, but can reach to 20 arcsec locally.

DOI： 10.1117/12.2190762

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Publishing type：Internal/External technical report, pre-print, etc.  

In this white paper we describe the prospects for ASTRO-H for the study of<br />
outflows from active galactic nuclei. The most important breakthroughs in this<br />
field are expected to arise from the high spectral resolution and sensitivity<br />
in the Fe-K band, combined with broad-band sensitivity over the full X-ray band<br />
and spectral capabilities also at lower energies. The sensitivity in the Fe-K<br />
region allows to extend the absorption measure distribution of the outflow out<br />
to the highest ionisation states accessible, where observations with current<br />
X-ray missions indicate that most of the outflowing gas is to be found. Due to<br />
the high-resolution and sensitivity it will also be able to give the definitive<br />
proof for the existence of ultra-fast outflows, and if so, characterise their<br />
physical properties in great detail. These ultra-fast outflows carry very large<br />
amounts of energy and momentum, and are of fundamental importance for feedback<br />
studies. We show how the ASTRO-H observations in general can help to constrain<br />
numerical models for outflows. The link to reflection and emission processes is<br />
also discussed, as well as the possible relation between outflows and<br />
relativistic emission lines. Finally, we discuss the prospects for other<br />
related categories of objects like BAL quasars, partially covered sources and<br />
Compton thick outflows.

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© 2014 SPIE. We study lightweight X-ray mirror with Carbon Fiber Reinforced Plastic (CFRP) substrate for next generation X-ray satellites. CFRP is suitable material as substrate for tightly nested X-ray mirrors like telescope of Suzaku, ASTRO-H because it has properties of higher strength-to-weight ratio and flexibility of forming than that of metals. In the current year we performed fabrication of flat panels for baseline study and monolithic Wolter-I shell substrates by multi-plies pre-pregs. We also performed reflector replication based on technique for the ASTRO-H/HXT mirror fabrication. In this paper the development of the study of CFRP substrate fabrication and reflector replication will be reported.

DOI： 10.1117/12.2054837

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ASTRO-H is an astrophysics satellite dedicated for non-dispersive X-ray spectroscopic study on selective celestial X-ray sources. Among the onboard instruments there are four Wolter-I X-ray mirrors of their reflectors' figure in conical approximation. Two of the four are soft X-ray mirrors(1), of which the energy range is from a few hundred eV to 15 keV within the effective aperture being defined by the nested reflectors' radius ranging between 5.8 cm to 22.5 cm. The focal point instruments will be a calorimeter (SXS) and a CCD camera (SXI), respectively. The mirrors were in quadrant configuration with photons being reflected consecutively in the primary and secondary stage before converging on the focal plane of 5.6 m away from the interface between the two stages. The reflectors of the mirror are made of heat-formed aluminum substrate of the thickness gauged of 152 mu m, 229 mu m, and 305 mu m of the alloy 5052 H-19, followed by epoxy replication on gold-sputtered smooth Pyrex cylindrical mandrels to acquire the X-ray reflective surface. The epoxy layer is 10 mu m nominal and surface gold layer of 0.2 mu m. Improvements on angular response over its predecessors, e.g. Astro-E1/Suzaku mirrors, come from error reduction on the figure, the roundness, and the grazing angle/radius mismatching of the reflecting surface, and tighter specs and mechanical strength on supporting structure to reduce the reflector positioning and the assembly errors.Each soft x-ray telescope (SXT), SXT-1 or SXT-2, were integrated from four independent quadrants of mirrors. The stray-light baffles, in quadrant configuration, were mounted onto the integrated mirror. Thermal control units were attached to the perimeter of the integrated mirror to keep the mirror within operating temperature in space. The completed instrument went through a series of optical alignment, thus made the quadrant images confocal and their optical axes in parallel to achieve highest throughput possible. Environmental tests were carried out, and optical quality of the telescopes has been confirmed. SXT-1 and -2 were tested with the broad but slightly divergent beam, up to 8 arc-minutes, at Goddard. The full characterization were carried out in Japan which includes: angular resolution, effective area in the energy range of similar to 0.4 - 12keV, off-axis response at various energies, etc. We report the calibration results of the SXT-1 and -2 that were obtained at NASA/Goddard and JAXA/ISAS. The detailed calibration are reported in the two papers in this conference: 9144-206, "Ground-based x-ray calibration of the ASTRO-H soft x-ray telescopes" by R. Iizuka et al. and 9144-207, "Revealing a detailed performance of the soft x-ray telescopes of the ASTRO-H mission" by T. Sato, et al. Some small but significant discrepancies existed between ISAS and Goddard measurements that were attributed to the difference of the X-ray beams - pencil beam vs divergent beam.

DOI： 10.1117/12.2056804

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© 2014 SPIE. The new Japanese X-ray Astronomy satellite, ASTRO-H will carry two identical hard X-ray telescopes (HXTs), which cover 5 to 80 keV, in order to provide new insights into frontier of X-ray astronomy. The HXT mirror surfaces are coated with Pt/C depth-graded multilayers to enhance hard X-ray effective area by means of Bragg reflection, and 213 mirror reflectors with a thickness of 0.22 mm are tightly nested confocally in a telescope. The production of FM HXT-1 and HXT-2 were completed in 2012 and 2013, respectively. The X-ray performance of HXTs were measured at the synchrotron radiation facility SPring-8/ BL20B2 Japan. The total effective area of two HXTs is about 350 cm2 at 30 keV and the angular resolution of HXT is about 1.'9 in half power diameter at 30 keV. The HXTs are in the clean room at ISAS for waiting the final integration test.

DOI： 10.1117/12.2054633

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© 2014 SPIE. The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions developed by the Institute of Space and Astronautical Science (ISAS), with a planned launch in 2015. The ASTRO-H mission is equipped with a suite of sensitive instruments with the highest energy resolution ever achieved at E > 3 keV and a wide energy range spanning four decades in energy from soft X-rays to gamma-rays. The simultaneous broad band pass, coupled with the high spectral resolution of ΔE ≤ 7 eV of the micro-calorimeter, will enable a wide variety of important science themes to be pursued. ASTRO-H is expected to provide breakthrough results in scientific areas as diverse as the large-scale structure of the Universe and its evolution, the behavior of matter in the gravitational strong field regime, the physical conditions in sites of cosmic-ray acceleration, and the distribution of dark matter in galaxy clusters at different redshifts.

DOI： 10.1117/12.2055681

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Language：English   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

The 6th Japanese X-ray satellite, ASTRO-H, equips two Hard X-ray Telescopes (HXTs) to perform imaging spectroscopy up to 70 keV. The 2nd flight module (HXT-2) had been completed in July, 2013. After some environmental tests were passed, the X-ray performance of the HXT-2 was measured at the SPring-8 BL20B2, 3rd generation synchrotron facility. The angular resolution defined with a Half Power Diameter (HPD) was 1'.9 at 30 keV and 1'.8 at 50 keV. This small energy dependence is considered to be caused by the difference in image quality of each foil; the inner mirror shells have better quality than outer ones. The effective area was found to be 178 cm(2) at 30 keV and 82 cm(2) at 50 keV, both of which exceed the requirement. Furthermore, the detailed energy dependence of the effective area was examined for a limited aperture in the 30-70 keV band with a pitch of 1 keV. We also measured the off-axis dependence of the effective area at 50 keV, and then determined the optical axis. The field of view of the HXT-2 was found to be 5'.6 (FWHM of the vignetting function), consistent with the simulation. In this paper, we also report the detailed analysis of the ground calibration data, which will be used for image reconstruction by a ray-tracing simulator.

DOI： 10.1117/12.2055656

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

CiNii Books

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

CiNii Books

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We report recent progresses on the fabrication of pre-collimators (PCs). The PCs are designed to mitigate lights for X-ray telescopes to be onboard ASTRO-II. Each PC consists of cylindrical aluminum shells (blades) with varying radii of 60-225 nun, alignment frames to guide the blade positions, and the blade housing body. The alignment frame and the housing are made of Aluminum 6061 and 7075 alloy, respectively. Heat-forming process is introduced to the production to stabilize the blade shape in orbit. Precise curvature of radius (tolerance of 1 ram) and the linearity along with the direction of incident X-rays (RV. &lt; 20 mu m) ensure that the blades do not obscure the telescope aperture. Each PC blade is placed precisely on top of the respective reflector mirror shell to reduce off-axis X-ray photons that leads to a "ghost" image within the detector field of view. In September 2010, the PC design its height, thickness, and material of blades was fixed and we produced the engineering model (FM) for the Soft X-ray Telescopes (SXTs). Si nee then, vibration tests for the EM PC unit are carried out twice, verifying that the PC has sufficient structural strength to withstand severe conditions during its launch. The EM PC is also installed onto the SXT mirror housing fabricated at the NASA's GSFC to validate our PC assembly method without any loss of the telescope's effective aperture area. Since August 2011, we have been manufacturing the PC blades for the flight models. We hereby show the in processes and also results of stray-light measurement without PCs for the SXT EM (obtained at ISAS 30m beamline facility) and the HXT FM (obtained at SPring-8 synchrotron radiation facility).

DOI： 10.1117/12.925902

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

ASTRO-H is an international X-ray mission of ISAS/JAXA, which will be launched in 2014. One of the main characteristics of ASTRO-H is imaging spectroscopy in the hard X-ray band above 10 keV. ASTRO-H will carry two identical Hard X-ray telescopes (HXTs), whose mirror surfaces are coated with Pt/C depth-graded multilayers to enhance hard X-ray effective area up to 80 keV. HXT was designed based on the telescope on board the SUMIT balloon borne experiment. After feasibility study of the HXT design, the FM design has been deteremined. Mass production of the mirror shells at Nagoya University has been going on since August 2010, and production of mirror shells for HXT-1 was completed in March 2012. After the integation of X-ray mirrors for HXT-1, we measured hard X-ray performance of selected mirror shells for HXT-1 at a synchrotron radiation facility, SPring-8 beamline BL20B2. We will perform environment tests and ground calibarations at SPring-8 for HXT-1. In HXT-2, foil production is going on. © 2012 SPIE.

DOI： 10.1117/12.926753

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

ASTRO-H is a next version of Japanese X-ray astronomy satellite for lunch in 2014. The hard X-ray telescope (HXT) on board the satellite has a cylindrical mirror housing which contains reflection circular mirror foils. In the present paper, vibration properties of the mirror foils installed in the HXT on-board a satellite were investigated. Vibration tests and FEM analysis of mirror foils installed in the part model of HXT were conducted. From the experimental results, it appeared that the mirror had resonant frequencies at 64, 73 and 118Hz. The modal shapes of 64 and 73Hz peaks showed that the maximum amplitude appeared at edges of the foil. On the other hand, vibration amplitude became maximum at the center in the modal shape of 118Hz peak. In addition, it appeared that the first peak of the edge mode decreased with increasing acceleration while the second peak had weak dependency on acceleration. These vibration behaviors are thought to be governed degree of constraint of the connections between the foil and alignment bars. © 2012 SPIE.

DOI： 10.1117/12.925864

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)  

The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly successful X-ray missions initiated by the Institute of Space and Astronautical Science (ISAS). ASTRO-H will investigate the physics of the highenergy universe via a suite of four instruments, covering a very wide energy range, from 0.3 keV to 600 keV. These instruments include a high-resolution, high-Throughput spectrometer sensitive over 0.3-12 keV with high spectral resolution of ?E 5 7 eV, enabled by a micro-calorimeter array located in the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers covering 5-80 keV, located in the focal plane of multilayer-coated, focusing hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12 keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the 40-600 keV band. The simultaneous broad bandpass, coupled with high spectral resolution, will enable the pursuit of a wide variety of important science themes. © 2012 SPIE.

DOI： 10.1117/12.926190

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Language：English   Publishing type：Article, review, commentary, editorial, etc. (international conference proceedings)   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

We present recent results of hard X-ray characterization of ASTRO-H HXT at SPring-8. The HXT onboard ASTRO-H is thin-foil, multi-nested conical optics similar to the Suzaku X-ray telescope. To reflect hard X-rays efficiently, reflector surface is coated with depth-graded Pt/C multilayer. The integraion of the HXT-1 mirror module has been completed. This mirror module has been characterized at a synchrotron radiation facility, SPring-8 beamline BL20B2. We have adopted, newly, an active tuning procedure with piezoelectric actuator to improve a focused image confocality. We have measured point spread function and effective area at 30, 40, 50, and 60 keV. An angular resolution of 1.9 arcmin (HPD) at 30 keV was obtained in the full telescope. The effective area of HXT-1 at 30 keV meets the requirements of HXT.

DOI： 10.1117/12.927271

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Language：Japanese   Publisher：The Japan Society of Mechanical Engineers  

In the present paper, vibration properties of mirror foils installed in a hard X-ray telescope (HXT) on-board a satellite were investigated. Vibration tests and FEM analysis of mirror foils installed in the part model of HXT were conducted. From the experimental results, it appeared that the mirror had resonant frequencies at 64, 73 and 11 OHz. The modal shapes of 64 and 73Hz showed that the maximum amplitude appeared at edges of the foil. On the other hand, vibration amplitude became maximum at the center in the modal shape of 11 OHz. Experimental results of frequency responses of these modes agreed well with analytical results except around 64Hz. It is considered that the resonant mode of 64Hz was strongly affected by nonlinear characteristics of friction constraint between the foils and HXT housing.

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We present the current status of the pre-collimator for the stray-light reduction, mounted on the ASTRO-H X-Ray Telescopes (XRT). Since the ASTRO-H XRTs adopt the conical approximation of the Wolter-I type grazing incident optics, X-rays from a source located far from the telescope boresight create a ghost image in the detector field of view (FOV) as a stray light, and then reduce the signal-to-noise ratio even in the hard X-ray band. We thus plan to mount the pre-collimator, which is comprised of cylindrical blades aligned with each primary mirror, onto the XRTs to remove the stray light. While the pre-collimator for the Soft X-ray Telescopes is designed by the similar principle adopted for the Suzaku pre-collimator, that for the Hard X-ray Telescopes requires some trade-off studies to select an appropriate blade material. The HXT pre-collimator currently utilizes the aluminum blade with the 50 mm height and 150 mu m thickness. We examined the observational effects by the hard X-ray (> 10 keV) stray light and the expected performance of the pre-collimator in some scientific cases, using a ray-tracing simulator. We found that the Galactic center may be mostly covered with the stray light from the well-known bright X-ray sources. In addition, the flux estimation of the extended X-ray emission such as the Cosmic X-ray Background is also found to have large (similar to 30%) uncertainty due to the stray light from the outside of the XRT FOV. The pre-collimator improves the situations; the stray light covering the source-free region in the Galactic center can be reduced by half and the uncertainty of the flux determination for the diffuse source decreases down to < 10%.

DOI： 10.1117/12.856803

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

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Language：English   Publisher：Japan Aerospace Exploration Agency (JAXA)  

The 3rd Suzaku international Conference "Energetic Cosmos : from Suzaku to ASTRO-H" (June 29-July 2, 2009. Grand Park Otaru Hotel), Otaru, Hokkaido JapanWe present results from observations of three ultraluminous infrared galaxies(ULIRGs) with Suzaku and XMM-Newton. Their optical emission lines are classified as seyfert 2 and extinction-corrected [OIII]lambda5007 line luminosities are (3.2 - 61) x 10 (sup 43) erg s(sup -1), which are in the range for quasars. Their X-ray spectra are explained by a combination of unabsorbed and absorbed power-law components. Fe Kalpha lines are not detected. The absorption-corrected 2-10 keV luminosities L(sub (2 - 10 keV)) are in the range of (3.3 - 24) x 10(sup 42) erg s(sup -1). These results indicate that these objects are Compton-thin AGNs with Seyfert class luminosity. We compare the far infrared (FIR) luminosities L(sub FIR) with the bolometric luminosities of the AGNs and find that the contribution of AGNs to L(sub FIR) is at most a few tens of percent.Meeting sponsors: The University of Tokyo, The Institute of Physical and Chemical Research, The Japan Society for the Promotion of Science

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ASTRO-H is the new Japanese X-ray astronomy satellite for launch in 2013. HXT on board the satellite has a mirror housing which is a cylindrical case and contains reflection mirror foils, which are constrained by alignment bars. In order to investigate vibration properties of HXT on board the satellite, vibration tests and FEM analyses were conducted. From the results of x-vibration test, it was found that there were no resonant frequencies at frequency less than 120 Hz. It also appeared that foils move along grooves of alignment bars when the housing was vibrated because kinetic connection between foils and alignment bars is only friction force. From the simulated results, this loose connection used in the actual HXT housing is useful to suppress a strong resonance at 51Hz predicted by supposing tight connections such as adhesiveness. As for z-vibration properties, vibration property of the housing was complicated since foils leap when zacceleration becomes larger than 1G. However it could be confirmed that the distinct resonant peaks did not appear at frequency less than 200 Hz. From these results, it was found that HXT housing had not any resonant frequencies less than 120 Hz, which is the maximum frequency of sinusoidal vibrations applied when launched. © 2010 SPIE.

DOI： 10.1117/12.856846

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The new Japanese X-ray Astronomy satellite, ASTRO-H will carry two identical hard X-ray telescopes (HXTs), which cover 5 to 80 keV. The HXT mirrors employ tightly-nested, conically-approximated thin-foil Wolter-I optics, and the mirror surfaces are coated with Pt/C depth-graded multilayers to enhance hard X-ray effective area by means of Bragg reflection. The HXT comprises foils 450 mm in diamter and 200 mm in length, with a focal length of 12 m. To obtain a large effective area, 213 aluminum foils 0.2 mm in thickness are tightly nested confocally. The effective area is expected to be ∼ 310 cm2 at 30 keV and the image quality to be ∼1.7′ in half-power diameter. © 2010 SPIE.

DOI： 10.1117/12.856892

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The thin film technology called "depth-graded multi-layer" is used to manufacture reflector foils, which are inserted in a hard X-ray telescope. When the temperature of the foil changes from the temperature at which the foil was produced; thermal deformation is induced due to difference of linear coefficient of expansion of its constituents. The deformation causes performance of X-ray image formation to deteriorate. Therefore, it is absolutely imperative to estimate the amount of deformation quantitatively and to establish a method of temperature control for the foil under the thermal environment on orbit. We used the hard X-ray telescope, which is part of the currently-projected the ASTRO-H X-ray satellite, as an example for investigation. The effective method of the HXT thermal control was examined with the thermal analytical software, "Thermal Desktop". The deformation of the foil when the temperature was changed by 1 degree C was predicted by a finite element analysis (FEA). The thermal desktop analysis shows that the overall foil temperature in orbit can be close to the temperature at which the foils were produced (∼22degree C) by the newly developed thermal control method. The FEM analysis shows that the prediction of the foil deformation due to a temperature change of 1 degree C is about 8 μm. © 2010 SPIE.

DOI： 10.1117/12.856581

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Astro-H mission is the new Japanese X-ray mission following Suzaku. One of the unique features of the mission is an imaging spectroscopy in a unprecedentedly wide energy region from 0.3 to 60 keV. The X-Ray Telescope (XRT) system covers the energy region by means of grazing incidence reflective optics. In the current baseline specification, the XRT system consists of two hard X-ray telescopes (HXTs) which cover 5 to 60 keV, and two soft X-ray telescopes (SXT-S and SXT-I) which cover 0.3 to about 10 keV. Both of HXT and SXT-S mirrors employ tightly-nested, conicallyapproximated thin-foil Wolter-I optics. The HXTs employ Pt/C depth-graded multilayers (supermirrors), while the SXTS employ a single layer of gold. We measured test reflectors for Astro-H HXT at SPring-8, and obtained the roughness of the test reflectors of < 4 Ȧ and the image blur after two reflections of 0.8'-1.1'. International collaboration has been formed for the project, and basic and design studies have been carried out. Based on the basic study, detailed studies of the flight design are in progress, and production facilities for the Astro-H XRT system are close to complete.© 2009 SPIE.

DOI： 10.1117/12.826004

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We present a study on housing design for the X-ray telescopes (XRT) onboard the New Exploration X-ray Telescope (NeXT). The NeXT XRTs are larger than previous thin-foil XRTs. The XRT is required to have a sufficient stiffness in order to keep the high performance of the XRT in orbit. We performed a structure analysis of the virtual model of the NeXT XRT housing using the FEA software Marc. A virtual model of the NeXT XRT was designed based on the XRT of the SUMIT balloon experiment. From the structure analysis of the virtual model by Marc, we found that the displacement of the XRT housing is small. The maximum displacement is a few Âμm, which is satisfied with our goal of 10 Âμm. On the other hand, the alignment bars show a large displacement up to about 90 Âμm. This is caused because the alignment bars become longer, and the total weight of the thin foils increases due to the larger effective area. This analysis indicates that we have to use stiff alignment bars without reducing the effective area. This result is useful to design a proto-model of the XRT housing. We will examine the result of this FEA analysis by measuring the displacement of the proto-model.

DOI： 10.1117/12.788788

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Language：English   Publisher：SPIE-INT SOC OPTICAL ENGINEERING  

Japan's NeXT mission has, been approved for the Phase-A in 2007. At, present NeXT is in the process of transition to the Phase-B. One of the unique freature of the mission is an imaging spectroscopy in unprecedentedly wide energy region from 0.5 to 80 keV. The X-Ray Telescope (XRT) system covers the energy by means of grazing incidence reflective optics. International collaboration has been formed for the project and design and basic study have been carried out so far. Current baseline specification includes two hard X-ray telescopes which are combined with the Hard X-ray. Imager (Si + CdTe pixel or strip) and cover 5 to 80 keV, and two soft, X-ray telescopes which cover 0.3 to about 20 keV, one combined with a high resolution X-ray micro-calorimeter and the other with an X-ray CCD. Both of hard and soft X-ray mirrors employ same optical design; tightly-nested conically-approximated thin-foil Wolter-I optics. The mission requirements for XRT system have been identified as 300 cm(2) at 30 keV for the hard X-ray telescope in total and 400 cm(2) at 6 keV for the soft X-ray telescope per unit. The requirement oil the point spread function is 1.7 arcmin in HPD, as well as the goal being 1.2 arcmin Based oil the current level of technology all the mission requirements are expected to be satisfied.

DOI： 10.1117/12.788736

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The New Exploration X-ray Telescope (NeXT) is an X-ray, astronomical observatory slated to be launched from Japan in 2013. Its objectives range from high resolution imaging and spectroscopy, below similar to 12 keV to studyiug the hard X-ray sky up to similar to 70 keV. To accomplish these goals, it will carry, among other instruments, 4 grazing incidence, imaging telescopes, two covering the soft X-ray band and the remaining the higher energies. The soft X-ray telescopes will be similar to ones flown onboard Suzaku, with a larger outer diameter (45 cm) and longer focal length (6 m). The NASA's GSFC foil mirror group is collaborating with the Nagoya University and ISAS/JAXA in the implementation of the the soft, X-ray mirrors. Our science driven goal is a &lt; 1.3' Half Power Diameter (HPD) Point Spread Function, improved from Suzaku similar to 1.7' HPD. We address important area in the fabrication process where we plan to make changes; (1) substrate shaping, (2) replication process, (3) reflector assembly, (4) alignment bar accuracy and (5) focal length miss match among segments. Having done some of them, we measured 1.26' HPD for 60-pair quadrant reflectors. But it still includes bad sectors (&gt; 1.8' HPD) towards the quadrant boundary, while most of middle sectors are at 1' HPD level. The bad sectors can be corrected with new assembly approach where we actively tune and then fix reflectors at their right position or whole conical shell reflectors instead of segmented ones. In this proceeding, we present a proposed NeXT soft X-ray telescope performance, report the current status of the development and introduce the new whole shell mirror.

DOI： 10.1117/12.789599

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We present the design of the pre-collimator for the X-ray telescopes (XRTs) onboard New X-ray Telescope (NeXT). The optical design adopted for the NeXT XRTs is conically-approximated Wolter-I type optics. The tightly-nested reflectors with thin substrates (150-300 mu m) enable us to achieve the large effective area and extremely light weight simultaneously. However. due to the packed reflector shells, X-rays from the outside of the XRT field of view occasionally arrive at the focal plane without the, normal double reflection (stray lights), and then produce a ghost image oil the detector. Thus. the stray-fights contamination degrades sensitivity of the source detection In order to reduce the stray lights efficiently, we plan to mount a, collimator onto each telescope (referred to as pre-collimator), which is similar to that equipped with the Suzaku XRTs. The pre-collimator consists of coaxially-nested cylindrical blades. each of which is aligned radially with the corresponding primary reflector. We, found the height of the pre-collimator blade to be similar to 100 mm that is required to block the X-rays with off-axis angles of 30'-50'. which are the main light pass of the stray lights for the NeXT XRTs.

DOI： 10.1117/12.789184

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Language：Japanese   Publisher：The Physical Society of Japan (JPS)  

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Language：English   Publisher：PROGRESS THEORETICAL PHYSICS PUBLICATION OFFICE  

We obtained broad-band spectra of Seyfert 2 galaxies observed with the X-ray satellite Suzaku. Their X-ray emissions were resolved into a weak power-law emission, an absorbed power-law emission, a reflection, and many emission lines. These are the first observations to resolve the spectra by a broad-band spectroscopy from 0.3 to 100 keV. Thank to the high quality spectra with Suzaku, we obtained information to investigate the structure of active galactic nuclei in detail.

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We give overview and the current status of the development of the Soft X-ray Imager (SXI) onboard the NeXT satellite. SXI is an X-ray CCD camera placed at the focal plane detector of the Soft X-ray Telescopes for Imaging (SXT-I) onboard NeXT. The pixel size and the format of the CCD is 24 × 24μm (IA) and 2048 × 2048 × 2 (IA+FS). Currently, we have been developing two types of CCD as candidates for SXI, in parallel. The one is front illumination type CCD with moderate thickness of the depletion layer (70 ∼ 100μm) as a baseline plan. The other one is the goal plan, in which we develop back illumination type CCD with a thick depletion layer (200 ∼ 300μm). For the baseline plan, we successfully developed the proto model 'CCD-NeXT1' with the pixel size of 12μm × 12μm and the CCD size of 24mm × 48mm. The depletion layer of the CCD has reached 75 ∼ 85μm. The goal plan is realized by introduction of a new type of CCD 'P-channel CCD', which collects holes in stead of electrons in the common 'N-channel CCD'. By processing a test model of P-channel CCD we have confirmed high quantum efficiency above 10 keV with an equivalent depletion layer of 300μm. A back illumination type of P-channel CCD with a depletion layer of 200μm with aluminum coating for optical blocking has been also successfully developed. We have been also developing a thermo-electric cooler (TEC) with the function of the mechanically support of the CCD wafer without standoff insulators, for the purpose of the reduction of thermal input to the CCD through the standoff insulators. We have been considering the sensor housing and the onboard electronics for the CCD clocking, readout and digital processing of the frame date.

DOI： 10.1117/12.670649

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Language：Japanese   Publisher：宇宙科学研究所  

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We report on design updates for the XIS (X-ray Imaging Spectrometer) on-board the Astro-E2 satellite. Astro-E2 is a recovery mission of Astro-E, which was lost during launch in 2000. Astro-E2 carries a total of 5 X-ray telescopes, 4 of which have XIS sensors as their focal plane detectors. Each XIS CCD camera covers a field of view of 19 × 19 arcmin in the energy range of 0.4-12 keV. The design of the Astro-E2 XIS is basically the same as that for Astro-E, but some improvements will be implemented. These are (1) CCD charge injection capability. (2) a revised heat-sink assembly, and (3) addition of a 55Fe radio-isotope on the door. Charge injection may be used to compensate for and calibrate radiation-induced degradation of the CCD charge transfer efficiency. This degradation is expected to become significant after a few year's operation in space. The new heat-sink assembly is expected to increase the mechanical reliability and cooling capability of the XIS sensor. The new radio-isotope on the door will provide better calibration data. We present details of these improvements and summarize the overall design of the XIS.

DOI： 10.1117/12.461313

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DOI： 10.1117/12.409119

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Language：English   Publisher：WILEY-V C H VERLAG GMBH  

Ne analyzed six bright low-luminosity AGNs observed by the X-ray satellite ASCA, and discovered that low-luminosity AGNs are harbors of super massive black holes with M-BH &gt; 5 x 10(6)M(.), where MBH is black hole mass. Since the estimated mass accretion rates (hereafter (M) over dot) were too small to create such super massive black holes, the (M) over dot in the past were probably larger than those at present. These galaxies would be candidates of QSO remnants.

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Language：Japanese   Publisher：一般社団法人日本物理学会  

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Language：English   Publisher：PERGAMON PRESS LTD  

The Japanese X-ray satellite, ASCA has observed 6 Seyfert 2 galaxies. We found the evidence of obscured nuclei in all galaxies, i.e. heavy absorption feature for four galaxies and strong lines probably produced by fluorescence for two galaxies. This result supports the unified scheme of AGNs, and is very important to reveal the nature of type 2 Seyferts, e.g. obscured nucleus, scattering region, etc. The thermal component is found in low energy band as well as non thermal emission for two galaxies, and it would originate from starburst activity. It is very important, considering the connection between AGN and Starburst galaxy. It may give us a hint of the galaxy evolution. (C) 1997 COSPAR.

DOI： 10.1016/S0273-1177(97)00042-2

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Language：Japanese   Publisher：素粒子論グループ 素粒子研究編集部  

宇宙背景X線放射(Cosmic X-ray Background; CXB)とは、あらゆる方向からほぼ等方、一様に地球に降り注ぐ背景放射である。その全強度は、電波の背景放射(CMB)に次いで非常に大きいが、未だその起源は謎に包まれている。その起源を求めて、今までにさまざまなモデルが提唱され、また観測が行なわれてきた。実際CXBの研究は、宇宙の大規模構造だけでなく、AGN統一モデルなどにも制約を与え得る興味深いものである。今回、CXBについての研究の現状についてのレビューと共に、我々がX線観測衛星「あすか」を使ったサーベイから得た最新の結果を報告する。

DOI： 10.24532/soken.93.3_C96

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We studied the proton damage effects of the X-ray CCD. We have measured X-ray CCD performances after the irradiation of energies at 2 and 9.5 MeV, and confirmed clear degradation of Charge Transfer Efficiency (CTE) and the energy resolution. To recover degraded CTE and the energy resolution, we tried the charge injection technique, and found the improvement of CTI and the energy resolution to be and 1/4 and 1/3, respectively. We also estimated the energy level of the deep trap, which causes the quantization of the dark current from the radiation-damaged pixels. The trap energy level is about 0.57eV, or near the center of forbidden band.

DOI： 10.1117/12.255999

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Language：Japanese   Publisher：一般社団法人日本物理学会  

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