研究者業績
基本情報
- 所属
- 国立研究開発法人宇宙航空研究開発機構 宇宙科学研究所 助教総合研究大学院大学 宇宙観測科学講座 飛翔体天文学分野 助教
- 学位
- 博士(理学)(1998年3月 京都大学)修士(理学)(1995年3月 京都大学)
- 研究者番号
- 80342624
- ORCID ID
https://orcid.org/0000-0002-9099-5755- J-GLOBAL ID
- 202001011170717781
- researchmap会員ID
- R000011919
論文
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ASTROPHYSICAL JOURNAL 808(1) 2015年7月We have analyzed XMM-Newton, Chandra, and Suzaku observations of three similarly aged, ejecta-dominated supernova remnants (SNRs), Kepler's SNR, Tycho's SNR, and SNR 0509-67.5, to investigate the properties of the SN ejecta and the circumstellar medium (CSM). By simply comparing the X-ray spectra, we find that line intensity ratios of iron-group elements (IGEs) to intermediate-mass elements (IMEs) for Kepler's SNR and SNR 050-967.5 are much higher than those for Tycho's SNR. Given that Tycho's SNR and SNR 0509-67.5 are thought to be the remnants of a typical SN Ia and an overluminous SN Ia, respectively, we argue that Kepler is the product of an overlumious SN Ia. This inference is supported by our spectral modeling, which reveals the IGE and IME masses, respectively, to be 0.95(-0.37)(+0.34) M-circle dot and 0.12(-0.05)(+0.19) M-circle dot (Kepler's SNR), 0.75(-0.15)(+0.51) M-circle dot and 0.34(-0.25)(+0.08) M-circle dot (SNR 0509-67.5), and 0.35(-0.15)(+0.55) M-circle dot and 0.70(-0.28)(+0.12) M-circle dot (Tycho's SNR). We find that the CSM component in Kepler's SNR consists of tenuous diffuse gas (similar to 0.3 M-circle dot) present throughout the entire remnant, plus dense knots (similar to 0.035 M-circle dot). Since both of them show N overabundance, their origin would be CNO-processed material from the progenitor system. The mass of the diffuse CSM allows us to infer the pre-SN mass-loss rate to be similar to 1.5 x 10(-5)(v(w)/10 km s(-1)) M-circle dot yr(-1). The dense knots have slow proper motions and relatively small ionization timescales; hence, they were likely located a few parsecs away from the progenitor at the explosion. We thus argue that Kepler's SN was an overluminous (91T-like) event that recently started to interact with the massive CSM. This supports the possible link between 91T-like SNe and "Ia-CSM" SNe.
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JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS 1(3) 2015年7月The ASTRO-H hard x-ray telescope (HXT) is designed to reflect hard x-rays with energies up to 80 keV. It will make use of thin-foil, multinested conical optics with depth-graded platinum/carbon (Pt/C) multilayers. We report on thermal stress tests of the HXT reflectors. The reflectors were fabricated on a heat-formed aluminum substrate of thickness gauged at 200 mu m of the alloy 5052. This was followed by an epoxy replication on Pt/C-sputtered smooth Pyrex cylindrical mandrels to acquire the x-ray reflective surface. For the thermal tests, the reflectors were maintained at three different temperatures: -5, 50, and 60 degrees C, respectively, for a week. We found that the surface of the reflectors were significantly changed at temperatures of 60 degrees C or higher. The change appears as wrinkles with a typical scale length of a few tens of microns. No changes on the surface were observed from the -5 and 50 degrees C samples. There was also no change in the x-ray reflectivity for these two temperatures. (C) The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 67(2) 2015年4月We present the results from deep Suzaku observations of the central region of the Perseus cluster. Bulbul et al. (2014, ApJ, 789, 13) reported the detection by XMM-Newton instruments of an unidentified X-ray emission line at an energy around 3.5 keV in spectra for the Perseus and other clusters. They argued for a possibility of the decay of sterile neutrino, a dark matter candidate. We examine Suzaku X-ray Imaging Spectrometer (XIS) spectra of the Perseus cluster for evidence in the 3.5 keV line and other possible dark matter features in the 2-6 keV energy band. In order to search for and constrain a weak line feature with the XIS, observations of the Crab Nebula are used to evaluate the system's effective area. We found no line feature at the claimed position with a systematic line flux upper limit at a half (1.5 eV in line equivalent width) of the claimed best-fitting value by Bulbul et al. (2014). We discuss this inconsistency in terms of instrumental calibration errors and modeling of continuum emission. Future prospects for high-energy resolution spectroscopy with ASTRO-H are presented.
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APPLIED OPTICS 53(32) 7664-7676 2014年11月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 cm(2) at 30 keV and an angular resolution of <1.7' in half-power 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 cm(2). (C) 2014 Optical Society of America
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ASTROPHYSICAL JOURNAL LETTERS 785(2) 2014年4月Supernova remnants (SNRs) retain crucial information about both their parent explosion and circumstellar material left behind by their progenitor. However, the complexity of the interaction between supernova ejecta and ambient medium often blurs this information, and it is not uncommon for the basic progenitor type (Ia or core-collapse) of well-studied remnants to remain uncertain. Here we present a powerful new observational diagnostic to discriminate between progenitor types and constrain the ambient medium density of SNRs using solely Fe K-shell X-ray emission. We analyze all extant Suzaku observations of SNRs and detect Fe K alpha emission from 23 young or middle-aged remnants, including five first detections (IC 443, G292.0+ 1.8, G337.2-0.7, N49, and N63A). The Fe Ka centroids clearly separate progenitor types, with the Fe-rich ejecta in Type Ia remnants being significantly less ionized than in core-collapse SNRs. Within each progenitor group, the Fe Ka luminosity and centroid are well correlated, with more luminous objects having more highly ionized Fe. Our results indicate that there is a strong connection between explosion type and ambient medium density, and suggest that Type Ia supernova progenitors do not substantially modify their surroundings at radii of up to several parsecs. We also detect a K-shell radiative recombination continuum of Fe in W49B and IC 443, implying a strong circumstellar interaction in the early evolutionary phases of these core-collapse remnants.
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SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY 9144 2014年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 cm(2) 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.
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SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY 9144 2014年The thirty-meter X-ray pencil beam line at the Institute of Space and Astronautical Science (ISAS) was utilized for ground-based calibrations of X-ray telescopes (XRTs) onboard the ASTRO-D, the ASTRO-E and the ASTRO-E2 satellites. Recent upsizing or downsizing of XRT required upgrade of the ISAS beam line. We replaced a vacuum chamber in which the stages had been installed by a new cylindrical chamber whose diameter and length are 1.8 m and 11.3 m, respectively. Stages on which a telescope and detectors had been mounted were also replaced. At same time, a new CCD consists of 1240 x 1152 pixels whose size are 22.5 x 22.5 mu m was introduced. The detector stage can be moved along the X-ray beam in the vacuum chamber, which allows us to change the distance between the sample and the detectors from 0.7 m to 9 m. The two stages can move in at least 500 x 500 mm(2) of square in the plane normal to the X-ray beam. The pitching of some moving axes are measured at 60 arcsec at most. The others are no more than about 30 arcsec. From April 2013, the ASTRO-H Soft X-ray telescopes (SXTs) have been calibrated at the new ISAS beam line.
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SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY 9144 2014年The X-ray astronomy satellite Astro-H, planed to be launched in 2015, will have several instruments for covering a wide energy band from a few hundreds eV to 600 keV. There are four X-ray telescopes, and two of them are soft X-ray telescopes (SXTs) covering up to about 15 keV. One is for an X-ray micro-calorimeter detector (SXS) and the other is for an X-ray CCD detector (SXI). The design of the SXTs is a conical approximation of the Wolter Type-I optics, which is also adopted for the telescopes on the previous mission Suzaku launched in 2005. It consists 203 thin-foil reflectors coated with gold monolayer (2000 angstrom) on the aluminum substrate (101.6 mm length) with the thickness of 0.15, 0.23 and 0.31 mm. These are nested confocally within the radius of 58 to 225 mm. The focal length of SXTs is 5.6 m. The weight is as light as similar to 43 kg per telescope.We present the current status of the calibration activity of two SXTs (SXT-1 and SXT-2). The developments of two SXTs were completed by NASA's Goddard Space Flight Center (GSFC). First X-ray measurements with a diverging beam at the GSFC 100m beamline found an angular resolution at 8.0 keV to be 1.1 and 1.0 arcmin (HPD) for SXT-1 and SXT-2, respectively. The full characterization of the X-ray performance has been now continuously calibrated with the 30m X-ray beamline facility at the Institute of Space and Astronautical Science (ISAS) of Japan Aerospace eXploration Agency (JAXA) in Japan. We adopted a raster scan method with a narrow X-ray pencil beam with the divergence of similar to 15". X-ray characterization of the two SXTs has been measured from May and December 2013, respectively.In the case of SXT-1, the on-axis effective area was approximately 580, 445, 370, 270, 185 and 90 cm(2) at energies of 1.5, 4.5, 8.0, 9.4, 11.1 and 12.9 keV respectively. The effective area of SXT-2 is 2% larger than that of SXT-1 irrespective to X-ray energy. The on-axis angular resolution of SXT-1 was evaluated as 1.3 - 1.5 arcmin (HPD) in the 1.5 13 keV band. The resolution was slightly got worse at higher energies by similar to 0.3 arcmin. Otherwise, the resolution of SXT-2 is 1.2 arcmin, almost irrespective to X-ray energy. The field of view (FOV) was similar to 16 arcmin at 1.5 keV, decreasing with increasing X-ray energy, and became 8 arcmin at 13 keV. The FOV is defined here as the full-width at half-maximum (FWHM) of the vignetting curve.The X-ray performance of SXT-1 and SXT-2 meets the system requirements. Because all the parameters of the SXT-2 is slightly better that of SXT-1, we adopted the SXT-2 telescope for the SXS detector of the Astro-H primary instrument with the narrow FOV.
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2014 IEEE 40TH PHOTOVOLTAIC SPECIALIST CONFERENCE (PVSC) 2161-2165 2014年This paper presents analysis results for the onorbit performance of a solar array paddle of the X-ray astronomy satellite Suzaku. The current generated by the solar array was decreasing significantly for approximate one year after mid-2011. We estimated the degradation of the output by simulating the on-orbit environment according to the JPL prediction method. The analysis results indicate that the on-orbit degradation of the solar array paddle is greater than the predicted performance degradation in a space environment. We determined that the difference between the on-orbit data and the analysis results could be attributed to either an increase in cell temperature or radiation degradation due to solar flares.
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SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY 9144 2014年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.
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SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY 9144 2014年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 Delta E <= 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.
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SPACE TELESCOPES AND INSTRUMENTATION 2014: ULTRAVIOLET TO GAMMA RAY 9144 2014年A Four-stage X-ray Telescope (FXT) has been developed as the best-fit optics for the Diffuse Intergalactic Oxygen Surveyor (DIOS) mission, a small satellite mission for mapping observations of the warm-hot intergalactic medium. The FXT mirrors are based on a conical approximation of the Wolter-I design, fabrication technique used in the Suzaku satellite. We made the second FXT demonstration model, in which we installed 4 sets of 4 stage mirrors with diameter of about 500 mm using alignment plate. Both optical and X-ray measurement were done to estimate FXT performance. Although angular resolution is two to three times worse than that of the requirement and the goal, the field of view and the effective area are consistent with expected performance derived by the ray tracing simulation.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 65(5) 2013年10月We observed an extended X-ray source, designated as Suzaku J1759-3450, with Suzaku and Chandra observations towards 1RXS J175911.0-344921, which is an unidentified X-ray source listed in the ROSAT Bright Source Catalogue. A conspicuous emission line at 6 keV was also found in the Suzaku J1759-3450 spectrum. Assuming the emission line to be K emission from He-like Fe ions, we inferred Suzaku J1759-3450 to be an extragalactic object located at z = 0.13. The radial profile of the surface brightness in the 0.5-10 keV band was explained well with an isothermal beta-model of r(c) = 1.'61 and beta = 0.78. The X-ray spectrum was well reproduced by an optically-thin thermal plasma with the electron temperature of kT(e) = 5.3 keV, attenuated by the photoelectric absorption of N-H = 2.3 x 10(21) cm(-2). The bolometric X-ray luminosity of L-X(r < r(500)) = 4.3 x 10(44) erg s(-1) is consistent with that expected from the L-X-T relation of clusters of galaxies. In terms of the spatial extent, the X-ray spectrum, and the bolometric luminosity of the X-ray emitting gas, we concluded that Suzaku J1759-3450 is a new cluster of galaxies.
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ADVANCES IN SPACE RESEARCH 51(7) 1278-1281 2013年4月We detected hard X-ray emission from the unidentified Galactic bulge source 1RXS J175721.2-304405 with ASCA. The observed absorption column, flux and power-law index led us to consider that 1RXS J175721.2-304405 may be a new low-mass X-ray binary located near the Galactic center. Furthermore, the X-ray light-curve shows a step-function-like time variability, which is likely due to the occultation of a companion star. Future follow-up observations by missions such as ASTROSAT may reveal a periodic eclipse from 1RXS J175721.2-304405 if it is covered long enough. Since the long orbital period suggests a giant companion, follow-up observations will give firm evidence that 1RXS J175721.2-304405 is a new and rare eclipsing low-mass X-ray binary with a giant companion. (C) 2012 COSPAR. Published by Elsevier Ltd. All rights reserved.
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OPTICS FOR EUV, X-RAY, AND GAMMA-RAY ASTRONOMY VI 8861 2013年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 cm(2) at 30 keV and 82 cm(2) 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.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 64(5) 2012年10月We present Suzaku observations of two unidentified sources towards the Galactic bulge, 1RXS J165256.3-264503 and 1RXS J174459.5-172640, both of which were discovered with the ROSAT All-Sky Survey. We obtained wide-band spectra of these sources above 2 keV for the first time. The X-ray spectrum of 1RXS J165256.3-264503 consists of two absorbed thin thermal plasma components with temperatures of 0.7 and 2.4 keV. An RS CVn star, HD 152178, was found within a 90% error circle of the source position. Due to this position coincidence, and an X-ray spectrum analogous to those of other RS CVn binaries, we concluded that 1RXS J165256.3-264503 is an RSCVn-type active binary. The X-ray spectrum of 1RXS J174459.5-172640 was dominated by continuum emission extending up to similar to 20 key, which can be explained by an absorbed cutoff power-law or a combination of absorbed multicolor disk-blackbody and Comptonized emission. We inferred that the source is a new Galactic-bulge low-mass X-ray binary (LMXB) with a luminosity of 2 x 10(35) erg s(-1), based on its X-ray spectrum and lightcurve. Hence, 1RXS J174459.5-172640 may be an intriguing example of an LMXB in an intermediate state in which X-ray emission mechanisms can be readily explored.
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SPACE TELESCOPES AND INSTRUMENTATION 2012: ULTRAVIOLET TO GAMMA RAY 8443 2012年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.
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SUZAKU 2011: EXPLORING THE X-RAY UNIVERSE: SUZAKU AND BEYOND 1427 2012年Since launch, the 3-axis attitude control using the Inertial Reference Unit (IRU) had been done with the combination of IRU-X/Z/S1. Recently, the output of the IRU-S1 had become noisy. We then switched over from the IRU-S1 to S2 at 03: 21 on 18th, December 2009. Since the switch, it was found that the accuracy of the attitude control and determination along the DET-X axis became worse than previous by roughly a factor of two, though it has been different from observation to observation. At June 15th, 2010, the other IRU-Y was activated not for the attitude control but for the determination. The activation recovers the pointing determination accuracy down to the level before the IRU-S1 was switched off.
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SPACE TELESCOPES AND INSTRUMENTATION 2012: ULTRAVIOLET TO GAMMA RAY 8443 2012年The ASTRO-H 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 reflectors are made of heat-formed aluminum substrate of the thickness gauged of 200 mu m of the alloy 5052, followed by epoxy replication on Pt/C-sputtered smooth Pyrex cylindrical mandrels to acquire the X-ray reflective surface. The epoxy layer is 20 mu m depth. In this paper, we report a thermal stress test of the reflectors of the HXT. The reflectors can experience in various temperature environment either in ground or in space. The temperature range can be as wide as several tens degrees in space dependently on the thermal design of the telescope system. We kept the reflectors in the three different temperatures at -5, 50 and 60 degrees, respectively, for a week. It is found that the surface of the reflectors at 60 degrees or higher temperature were significantly changed. The change appears as wrinkles with a typical scale length of a few tens micron meters. It is noticed that the scale length is equivalent to the depth of the epoxy layer, suggesting the existence of the epoxy layer causes the change in the scale length. No changes on the surface were observed from the -5 and 50 degree samples. No change on X-ray reflectivity was also detected from them.
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DEATH OF MASSIVE STARS: SUPERNOVAE AND GAMMA-RAY BURSTS (279) 351-352 2012年By monitoring WC7 and the O5.5 binary WR 140 with the Suzaku telescope, we demonstrate a new method to measure the mass loss rates of both stars. By using the absorption column density, we found a mass-loss rate for the WC7 component : M-wc7 approximate to 1.2 x 10(-5)M circle dot yr(-1). We also measured the mass-loss rate of the companion O component using a luminosity variation in phases: M-O5.5 approximate to 5 x 10(-7)M circle dot yr(-1).
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2012 INTERNATIONAL CONFERENCE ON OPTICAL MEMS AND NANOPHOTONICS (OMN) 87-+ 2012年We have been developing our original MEMS-based X-ray optics for future astronomical missions. To date, we verified the focusing of optical light and X-ray for the first time. The concept and recent advances are reviewed.
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SPACE TELESCOPES AND INSTRUMENTATION 2012: ULTRAVIOLET TO GAMMA RAY 8443 2012年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.
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SPACE TELESCOPES AND INSTRUMENTATION 2012: ULTRAVIOLET TO GAMMA RAY 8443 2012年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. < 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).
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SUZAKU 2011: EXPLORING THE X-RAY UNIVERSE: SUZAKU AND BEYOND 1427 2012年The young supernova remnant CTB 37B with a distance of 10.2 +/- 3.5 kpc have CXOU J171405.7-381031, which is known as a 3.8's pulsar. The observation of the pulsar with Suzaku (Nakamura et al. 2009) has exhibited some of the features, an example is very strong magnetic field (similar to 10(14-15) Gauss), which coincident with the class of the "Magnetor". The purposes of our similar to 120 ksec observation with XMM-Newton are to identify of the pulsar clearly by timing analysis and spectroscopy, and reveal the condition of the surrounding supernova remnant.
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SUZAKU 2011: EXPLORING THE X-RAY UNIVERSE: SUZAKU AND BEYOND 1427 2012年We present results of spectral studies of two Wolf-Rayet colliding wind binaries (WR 140 and WR 30a), using the data obtained by the Suzaku and XMM-Newton satellites. WR 140 is one of the best known examples of a Wolf-Rayet star. We executed the Suzaku X-ray observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. We detected hard X-ray excess in the HXD band (> 10 key) for the first time from a W-R binary. The luminosity of the dominant, high temperature component is not inversely proportional to the distance between the two stars. WR 30a is the rare WO-type W-R binary. We executed XMM-Newton observations and detected X-ray emission for the first time. The broad-band spectrum was well-fitted with double-absorption model. The hard X-ray emission was heavily absorbed. This can be interpreted that the hard X-ray emitting plasma exist near WO star.
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SPACE TELESCOPES AND INSTRUMENTATION 2012: ULTRAVIOLET TO GAMMA RAY 8443 2012年X-ray reflection mirror of the Soft X-ray Telescope onboard ASTRO-H was coated by gold thin layer. Gold have M-shell X-ray absorption edge around 2 keV which is included in the energy band covered with the focal plane detector such as Soft X-ray Imager and Soft X-ray Spectrometer. It is important to make response function taken int account the Au M-dege structure especially for the Soft X-ray Spectrometer because It has unprecedented high energy resolution of 5 eV from 0.3 to 12 keV. We performed the detailed measurements of of reflectivity of the mirror using reflectometer in the synchrotron radiation facility KEK PF BL-11B from Nov. 29, 2011 to Dec. 5. X-ray beam of BL-11B was monochromatized to E/deltaE of 5000 by Double crystal monochromator using Si(111). We obtained the reflectivity at the grazing incident angles of 1.0, 1.2, and 1.4 degrees. While the energy pitch was set to be 2 eV in the 2.1-4.1 keV band, the reflectivity in the 2.2-2.35 keV band was also measured in detail with the energy pitch of 0.25 eV. We report the results and optical parameters of the SXT mirror such as reflectivity, and roughness calculated from the measurements.
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SUZAKU 2011: EXPLORING THE X-RAY UNIVERSE: SUZAKU AND BEYOND 1427 2012年The stray light is one of the systematic uncertainties in the analysis of faint diffuse objects, such as outskirts of clusters of galaxies. The stray light had been modeled so that researchers can estimate it by xissim. The model prediction sometimes differs from the observation by factors. We summarize characteristics of stray lights obtained from Crab offset observations.
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SPACE TELESCOPES AND INSTRUMENTATION 2012: ULTRAVIOLET TO GAMMA RAY 8443 2012年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.
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OPTICS FOR EUV, X-RAY, AND GAMMA-RAY ASTRONOMY V 8147 2011年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 goion on since August 2010. We have introduced a new screening method for replication mandrels with optical images. 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.
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OPTICS FOR EUV, X-RAY, AND GAMMA-RAY ASTRONOMY V 8147 2011年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.
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APPLIED OPTICS 49(6) 1007-1011 2010年2月The x-ray reflectivity of an ultralightweight and low-cost x-ray optic using anisotropic wet etching of Si (110) wafers is evaluated at two energies, C K-alpha 0.28 keV and Al K-alpha 1.49 keV. The obtained reflectivities at both energies are not represented by a simple planar mirror model considering surface roughness. Hence, an geometrical occultation effect due to step structures upon the etched mirror surface is taken into account. Then, the reflectivities are represented by the theoretical model. The estimated surface roughness at C K-alpha (similar to 6 nm rms) is significantly larger than similar to 1 nm at Al K-alpha. This can be explained by different coherent lengths at two energies. (C) 2010 Optical Society of America
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2010 International Conference on Optical MEMS and Nanophotonics, Optical MEMS and Nanophotonics 2010 151-152 2010年An X-ray imaging test for an X-ray optical system based on MEMS technologies was conducted at the ISAS 30 m beamline. An X-ray reflection and focusing were successfully verified at Al Kα 1.49 keV for the first time. The image quality estimated as a half power diameter was ∼20 arcmin. This was consistent with the angular resolution estimated from the surface roughness of 200 nm rms at 100 ìm scale. In this paper, the experimental setup and the result of X-ray imaging analysis are reported. ©2010 IEEE.
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SPACE TELESCOPES AND INSTRUMENTATION 2010: ULTRAVIOLET TO GAMMA RAY 7732 2010年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.
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X-RAY ASTRONOMY-2009: PRESENT STATUS, MULTI-WAVELENGTH APPROACH AND FUTURE PERSPECTIVES, PROCEEDINGS 1248 295-+ 2010年We systematically analyzed 27 member galaxies in the Virgo cluster. Elongated Xray features are found in 10 out of 27 objects. Furthermore, we analyzed other 13 clusters with temperature of 1 - 10 keV to examine environmental effects on the galaxies' gas. We examined the size, the luminosity and the mass of 25 E/S0 galaxies in the various environments. Every parameter in X-ray gets significantly smaller and fainter as the ambient ICM pressure increases. Since the temperature of the ICM is proportional to the square of the velocity dispersion of galaxies, the trends are fully consistent with the ram pressure stripping scenario.
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SPACE TELESCOPES AND INSTRUMENTATION 2010: ULTRAVIOLET TO GAMMA RAY 7732 2010年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 z-acceleration 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.
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SPACE TELESCOPES AND INSTRUMENTATION 2010: ULTRAVIOLET TO GAMMA RAY 7732 2010年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 similar to 310 cm(2) at 30 keV and the image quality to be similar to 1.'7 in half-power diameter.
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DECIPHERING THE ANCIENT UNIVERSE WITH GAMMA-RAY BURSTS 1279 363-+ 2010年WR 140 is one of the best known examples of a Wolf-Rayet stars. We executed the Suzaku X-ray observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. The column density at periastron is about 30 times higher than that at pre-periastron, which can be explained as self-absorption by the Wolf-Rayet wind. The spectra are dominated by a line and continuum emission from a optically thin-thermal plasma. The strong Ne-K lines are evidence that the thermal plasma is shock-heated W-R wind materials by the interaction with the wind from the companion O star. We present the parameters of the wind, such as a mass-loss rate, which were calculated with the absorption and line emission in the spectra.
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SPACE TELESCOPES AND INSTRUMENTATION 2010: ULTRAVIOLET TO GAMMA RAY 7732 2010年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.
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SPACE TELESCOPES AND INSTRUMENTATION 2010: ULTRAVIOLET TO GAMMA RAY 7732 2010年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%.
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X-RAY ASTRONOMY-2009: PRESENT STATUS, MULTI-WAVELENGTH APPROACH AND FUTURE PERSPECTIVES, PROCEEDINGS 1248 9-+ 2010年We report the preliminary results of the Suzalcu observations of the W-R binary WR 140 (WC7+O5I). We executed the observations at four different epochs around periastron passage in Jan. 2009 to understand the W-R stellar wind as well as the wind-wind collision shocks. The total exposure was 210 ksec. We detected hard X-ray excess in the HXD band (> 10 keV) for the first time from a W-R binary. Another notable discovery was a soft component which is not absorbed even by the dense wind. The spectra can be fitted by three different components; one is for the stationary cool component with kT similar to 0.1 key, one for a dominant high temperature component with kT similar to 3 keV and one for the hardest power-low component with Gamma similar to 2. The column density at periastron is 30 times higher than that at pre-periastron, which can be explained as self-absorption by the W-R wind. The emission measure of the dominant, high temperature component is not inversely proportional to the distance between the two stars.
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SPACE TELESCOPES AND INSTRUMENTATION 2010: ULTRAVIOLET TO GAMMA RAY 7732 2010年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 Delta E similar to 7 eV provided by the micro-calorimeter will enable a wide variety of important science themes to be pursued.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 61(6) 1217-1228 2009年12月Suzaku X-ray observations of a young supernova remnant, Cassiopeia A, were carried out. K-shell transition lines from highly ionized ions of various elements were detected, including Chromium (Cr-K alpha at 5.61 keV). The X-ray continuum spectra were modeled in the 3.4-40keV band, summed over the entire remnant, and were fitted with a simplest combination of the thermal bremsstrahlung and the non-thermal cut-off power-law models. The spectral fits with this assumption indicate that the continuum emission is likely to be dominated by non-thermal emission with a cut-off energy at > 1 keV. The thermal-to-non thermal fraction of the continuum flux in the 4-10 keV band is best estimated as similar to 0.1. Non-thermal-dominated continuum images in the 4-14 keV band were made. The peak of the non-thermal X-rays appears at the western part. The peak position of the TeV gamma-rays measured with HEGRA and MAGIC is also shifted at the western part with the I-sigma confidence. Since the location of the X-ray continuum emission was known to be presumably identified with the reverse shock region, the possible keV-TeV correlations give a hint that the accelerated multi-TeV hadrons in Cassiopeia A are dominated by heavy elements in the reverse shock region.
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ASTROPHYSICAL JOURNAL LETTERS 705(1) L62-L66 2009年11月 査読有りThe results from Suzaku observations of the central region of the Perseus cluster are presented. Deep exposures with the X-ray Imaging Spectrometer provide high-quality X-ray spectra from the intracluster medium. X-ray lines from helium-like Cr and Mn have been detected significantly for the first time in clusters. In addition, elemental abundances of Ne, Mg, Si, S, Ar, Ca, Fe, and Ni are accurately measured within 10' (or 220 kpc) from the cluster center. The relative abundance ratios are found to be within a range of 0.8-1.5 times the solar value. These abundance ratios are compared with previous measurements, those in extremely metal-poor stars in the Galaxy, and theoretical models.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 61(5) 1093-1098 2009年10月We showed that if the non-thermal emission from the galactic center in the range 14-40keV is due to inverse bremsstrahlung emission of subrelativistic protons, their interactions with hot and cold fractions of the interstellar medium are equally important. Our estimation shows that about 30% of the total non-thermal flux from the GC in the range 14-40keV is generated in regions of cold gas while the rest is produced by proton interaction with hot plasma. From the spatial distribution of 6.7 keV iron line we concluded the spatial distribution of hot plasma is strongly non-uniform that should be taken into account in analysis of proton propagation in the GC. From the Suzaku data we got independent estimates for the diffusion coefficient of subrelativistic protons in the GC, which was in the range 10(26)-10(27) cm(2) s(-1).
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 61(5) 1099-1105 2009年10月We analyse new results of Chandra and Suzaku Observatories which found a flux of hard X-ray emission from the compact region around Sgr A* (r similar to 100pc). We suppose that this emission is generated by accretion processes onto the central supermassive blackhole when an unbound part of captured stars obtains an additional momentum. As a result a flux of subrelativistic protons is generated near the galactic center which heats the background plasma up to temperatures about 6-10keV and produces by inverse bremsstrahlung a flux of non-thermal X-ray emission in the energy range above 10 keV.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 61(4) 901-907 2009年8月We analyze the 6.4 keV line and continuum emission from the molecular cloud Sgr B2 and the source HESS J1745-303, which is supposed to be a complex of molecular gas. From the HESS results it follows that Sgr A* is a source of high energy protons, which penetrate into molecular clouds producing there a TeV gamma-ray flux. We present arguments that Sgr A* may also produce a flux of subrelativistic protons which generate the 6.4 keV line and bremsstrahlung continuum emission from the clouds.
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OPTICS FOR EUV, X-RAY, AND GAMMA-RAY ASTRONOMY IV 7437 2009年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, conically-approximated thin-foil Wolter-I optics. The HXTs employ Pt/C depth-graded multilayers (supermirrors), while the SXT-S 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 angstrom 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.
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OPTICS FOR EUV, X-RAY, AND GAMMA-RAY ASTRONOMY IV 7437 2009年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
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ADVANCES IN X-RAY/EUV OPTICS AND COMPONENTS IV 7448 2009年We have been developing a thin-foil-nested X-ray telescope (XRT) for the Japanese X-ray astronomy satellites since ASCA launched in 1993. The thin-foil-nested XRT is advantageous in realizing high throughput with a light weight, whilst its angular resolution is poorer than other mirrors using, for example, a polished thick glass substrate onboard Chandra. We have investigated causes of image degradation of our XRT, and have identified them as figure error and positioning error of the reflectors. Since the latter dominates the entire error budget, we first attempted to improve the positioning error, and adopted the following two methods. First, we substituted an alignment plate for the alignment bar. The alignment plate incorporates the independently movable four alignment bars adopted for ASCA and Suzaku into a single plate. In practice, we allocated a pair of the plate in each slot, and after inserting all the reflectors, we shifted one of the plates radially to tightly hold the reflectors. Second, we have manufactured a partially replicated foil in which reflecting material (Au) is not applied to the axial edges of the foils in order to control the foil position by the edges of the reflectors whose thickness variation is within 2 mu m. After these improvements on the positioning error, we moved onto the figure error issue. With X-ray and laser profilometer measurements, we found that the figure error increased in a area closer to the azimuthal edges of the reflector. After considerable struggle for improvement, we finally decided to produce a long reflector and to cut both azimuthal edges. Thanks to these new devices, we have reduced the positioning error from 1.5 arcmin to 0.66. Furthermore, we have successfully produced 40-pairs of reflectors whose figure error is less than 0.8 arcmin. Incorporating these reflectors into a mirror housing, we have measured the XRT performance in the 30 m beamline facility at ISAS/JAXA, and confirmed to achieve an angular resolution of 1.08 arcmin in half-power diameter. The effective area is measured to be 14.0 cm(2), which is similar to 90% of the designed value. Note that this number is significantly enhanced from similar to 80% in the Suzaku XRT, which is a by-product of the improvement of the angular resolution.
MISC
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大気球シンポジウム: 2022年度 = Balloon Symposium: 2022 2022年11月大気球シンポジウム 2022年度（2022年11月7-8日. ハイブリッド開催（JAXA相模原キャンパス& オンライン)) Balloon Symposium 2022 (November 7-8, 2022. Hybrid(in-person & online) Conference (Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency (JAXA)(ISAS)), Sagamihara, Kanagawa Japan 著者人数: 87名 資料番号: SA6000177030 レポート番号: isas22-sbs-030
講演・口頭発表等
5-
44th COSPAR Scientific Assembly 2022年
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nuclear burning in massive stars – towards the formation of binary black holes – 2021年7月28日
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Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray 2020年12月19日
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The 15th Symposium of Japanese Research Community on X-ray Imaging Optics 2019年10月26日 招待有り
担当経験のある科目(授業)
6-
2023年9月 - 2024年3月
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2021年4月 - 2022年3月宇宙理学概論(オムニパス) (総合研究大学院大学)
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2019年10月 - 2020年3月宇宙理学概論(オムニパス) (総合研究大学院大学)
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2009年10月 - 2010年3月応用物理学講義 (中央大学)
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2009年4月 - 2009年9月宇宙物理学講義 (中央大学)
共同研究・競争的資金等の研究課題
11-
日本学術振興会 科学研究費助成事業 2023年4月 - 2027年3月
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2022年4月 - 2025年3月
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日本学術振興会 科学研究費助成事業 基盤研究(A) 2020年4月 - 2023年3月
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日本学術振興会 科学研究費助成事業 挑戦的研究(萌芽) 2019年6月 - 2022年3月
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日本学術振興会 科学研究費助成事業 新学術領域研究(研究領域提案型) 2013年4月 - 2015年3月
