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 宇宙物理学研究系 教授総合研究大学院大学 先端学術院 宇宙科学コース 教授東京工業大学 理学院物理学系物理学コース 特定教授関西学院大学 大学院理工学研究科 客員教授
- 学位
- 理学博士(東京大学)
- J-GLOBAL ID
- 200901025041369206
- researchmap会員ID
- 1000144439
専門はＸ線天文学。特に、中性子星やブラックホールを含むX線連星の観測的研究および衛星搭載X線CCDカメラの開発研究。
受賞
1-
1996年
論文
213-
Publications of the Astronomical Society of Japan 2024年10月10日Abstract We present an initial analysis of the X-Ray Imaging and Spectroscopy Mission (XRISM) first-light observation of the supernova remnant (SNR) N 132D in the Large Magellanic Cloud. The Resolve microcalorimeter has obtained the first high-resolution spectrum in the 1.6–10 keV band, which contains K-shell emission lines of Si, S, Ar, Ca, and Fe. We find that the Si and S lines are relatively narrow, with a broadening represented by a Gaussian-like velocity dispersion of $\sigma _v \sim 450$ km s$^{-1}$. However, the Fe He$\alpha$ lines are substantially broadened with $\sigma _v \sim 1670$ km s$^{-1}$. This broadening can be explained by a combination of the thermal Doppler effect due to the high ion temperature and the kinematic Doppler effect due to the SNR expansion. Assuming that the Fe He$\alpha$ emission originates predominantly from the supernova ejecta, we estimate the reverse shock velocity at the time when the bulk of the Fe ejecta were shock heated to be $-1000 \lesssim V_{\rm rs}$ (km s$^{-1}$) $\lesssim 3300$ (in the observer frame). We also find that Fe Ly$\alpha$ emission is redshifted with a bulk velocity of $\sim 890$ km s$^{-1}$, substantially larger than the radial velocity of the local interstellar medium surrounding N 132D. These results demonstrate that high-resolution X-ray spectroscopy is capable of providing constraints on the evolutionary stage, geometry, and velocity distribution of SNRs.
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Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 81-81 2024年9月10日
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The Astrophysical Journal Letters 973(1) L25-L25 2024年9月1日Abstract We present an analysis of the first two XRISM/Resolve spectra of the well-known Seyfert-1.5 active galactic nucleus (AGN) in NGC 4151, obtained in 2023 December. Our work focuses on the nature of the narrow Fe K α emission line at 6.4 keV, the strongest and most common X-ray line observed in AGN. The total line is found to consist of three components. Even the narrowest component of the line is resolved with evident Fe K α,1 (6.404 keV) and K α,2 (6.391 keV) contributions in a 2:1 flux ratio, fully consistent with neutral gas with negligible bulk velocity. Subject to the limitations of our models, the narrowest and intermediate-width components are consistent with emission from optically thin gas, suggesting that they arise in a disk atmosphere and/or wind. Modeling the three line components in terms of Keplerian broadening, they are readily associated with (1) the inner wall of the “torus,” (2) the innermost optical “broad-line region” (or “X-ray BLR”), and (3) a region with a radius of r ≃ 100 GM/c 2 that may signal a warp in the accretion disk. Viable alternative explanations of the broadest component include a fast-wind component and/or scattering; however, we find evidence of variability in the narrow Fe K α line complex on timescales consistent with small radii. The best-fit models are statistically superior to simple Voigt functions, but when fit with Voigt profiles the time-averaged lines are consistent with a projected velocity broadening of FWHM . Overall, the resolution and sensitivity of XRISM show that the narrow Fe K line in AGN is an effective probe of all key parts of the accretion flow, as it is currently understood. We discuss the implications of these findings for our understanding of AGN accretion, future studies with XRISM, and X-ray-based black hole mass measurements.
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 228-228 2024年8月21日
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Cryogenics 138 103795-103795 2024年3月
MISC
200-
日本物理学会講演概要集 65(1) 102-102 2010年3月1日
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宇宙航空研究開発機構特別資料: = JAXA Special Publication: The Energetic Cosmos; from Suzaku to ASTRO-H (9) 414-415 2010年2月26日著者人数: 25人(含チーム1)資料番号: AA0064574159レポート番号: JAXA-SP-09-008E
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Proceedings of SPIE - The International Society for Optical Engineering 7732 2010年© 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.
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Journal of the Korean Physical Society 54(6,Pt.1) 2552-2565 2009年
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61(SUPPL. 1) 2008年10月6日The charge transfer inefficiency (CTI) of the X-ray CCDs on board the Suzaku<br /> satellite (X-ray Imaging Spectrometers; XIS) has increased since the launch due<br /> to radiation damage, and the energy resolution has been degraded. To improve<br /> the CTI, we have applied a spaced-row charge injection (SCI) technique to the<br /> XIS in orbit; by injecting charges into CCD rows periodically, the CTI is<br /> actively decreased. The CTI in the SCI mode depends on the distance between a<br /> signal charge and a preceding injected row, and the pulse height shows periodic<br /> positional variations. Using in-flight data of onboard calibration sources and<br /> of the strong iron line from the Perseus cluster of galaxies, we studied the<br /> variation in detail. We developed a new method to correct the variation. By<br /> applying the new method, the energy resolution (FWHM) at 5.9 keV at March 2008<br /> is ~155 eV for the front-illuminated CCDs and ~175 eV for the back-illuminated<br /> CCD.
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61(SUPPL. 1) 2008年9月22日The X-ray Imaging Spectrometer (XIS) on board the Suzaku satellite is an<br /> X-ray CCD camera system that has superior performance such as a low background,<br /> high quantum efficiency, and good energy resolution in the 0.2-12 keV band.<br /> Because of the radiation damage in orbit, however, the charge transfer<br /> inefficiency (CTI) has increased, and hence the energy scale and resolution of<br /> the XIS has been degraded since the launch of July 2005. The CCD has a charge<br /> injection structure, and the CTI of each column and the pulse-height dependence<br /> of the CTI are precisely measured by a checker flag charge injection (CFCI)<br /> technique. Our precise CTI correction improved the energy resolution from 230<br /> eV to 190 eV at 5.9 keV in December 2006. This paper reports the CTI<br /> measurements with the CFCI experiments in orbit. Using the CFCI results, we<br /> have implemented the time-dependent energy scale and resolution to the Suzaku<br /> calibration database.
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日本物理学会講演概要集 63(2) 89-89 2008年8月25日
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Publ.Astron.Soc.Jap.60:S11-S24,2008 2008年3月5日One of the advantages of the X-ray Imaging Spectrometer (XIS) system on board<br /> Suzaku is its low and stable non-X-ray background (NXB). In order to make the<br /> best use of this advantage, modeling the NXB spectra with high accuracy is<br /> important to subtract them from the spectra of on-source observations. We<br /> construct an NXB database by collecting XIS events when the dark Earth covers<br /> the XIS FOV. The total exposure time of the NXB data is about 785 ks for each<br /> XIS. It is found that the count rate of the NXB anti-correlates with the<br /> cut-off-rigidity and correlates with the count rate of the PIN upper<br /> discriminator (PIN-UD) in Hard X-ray Detector on board Suzaku. We thus model<br /> the NXB spectrum for a given on-source observation by employing either of these<br /> parameters and obtain a better reproducibility of the NXB for the model with<br /> PIN-UD than that with the cut-off-rigidity. The reproducibility of the NXB<br /> model with PIN-UD is 4.55-5.63% for each XIS NXB in the 1-7 keV band and<br /> 2.79-4.36% for each XIS NXB in the 5-12 keV band for each 5 ks exposure of the<br /> NXB data. This NXB reproducibility is much smaller than the spatial fluctuation<br /> of the cosmic X-ray background in the 1-7 keV band, and is almost comparable to<br /> that in the 5-12 keV band.
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PASJ : publications of the Astronomical Society of Japan 60(1) S57-S68 2008年2月20日The accretion-powered pulsar Her X-1 was observed with Suzaku twice in its main-on state, on 2005 October 5-6 and 2006 March 29-30, for a net exposure of 30.5 ks and 34.4 ks, respectively. In the 2005 and 2006 observations, the source was detected at an average 10-30 keV intensity of 290 mCrab and 230 mCrab, respectively. The intrinsic pulse period was measured on both occasions at 1.23776 s by HXD-PIN, after barycentric and binary corrections. The pulse phase-averaged spectra in the energy range above 10 keV were well fitted by the "Negative and Positive power-law times EXponential" (NPEX) model, multiplied by a fundamental cyclotron resonance scattering feature at similar to 36 keV, which appears very significantly in the HXD-PIN data. The resonance profiles were successfully reproduced by a Lorentzian-type scattering cross section, rather than by a Gaussian-type alternative. The pulse phase-averaged HXD-GSO data, covering 50-120 keV, are featureless. However, in a differential spectrum between the pulse-decay phase and off-pulse phase, the second-harmonic cyclotron resonance was detected in the GSO data at similar to 73 keV, with a depth of 1.6(-0.7)(+0.9) This makes Her X-1 a 6th pulsar with established second-harmonic resonance. The implications of these results are briefly discussed.
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Proceedings of SPIE - The International Society for Optical Engineering 7011 2008年 査読有り
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日本物理学会講演概要集 62(2) 106-106 2007年8月21日
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Publications of the Astronomical Society of Japan 59 2007年4月8日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. © 2007. Astronomical Society of Japan.
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Publications of the Astronomical Society of Japan 59(1 SPEC. ISS.) 2007年4月8日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) onboard 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 0.2-12keV with energy resolution of 130eV at 5.9 keV, and a field of view of 18′ × 18′ are realized. Since the Suzaku launch on 2005 July 10, the XIS has been functioning well. © 2007. Astronomical Society of Japan.
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日本物理学会講演概要集 62(1) 94-94 2007年2月28日
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PASJ : publications of the Astronomical Society of Japan 59(1) S185-S198 2007年1月31日
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ASTROPHYSICAL JOURNAL 651(1) 615-616 2006年11月
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日本物理学会講演概要集 61(2) 76-76 2006年8月18日
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Proceedings of SPIE - The International Society for Optical Engineering 6266 II 2006年 査読有り
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HIGH-ENERGY DETECTORS IN ASTRONOMY 5501 296-303 2004年 査読有りNeXT is the X-ray satellite proposed for the next Japanese space science mission. While the satellite total mass and the launching vehicle are similar to the prior satellite Astro-E2, the sensitivity is much improved; it requires all the components to be lighter and faster than previous architecture. This paper shows the data processing architecture of the X-ray CCD camera system SXI (Soft X-ray Imager), which is the top half of the WXI (Wide-band X-ray Imager) of the sensitivity in 0.2-80 keV. The system is basically a variation of Astro-E2 XIS, but event extraction speed is much faster than it to fulfill the requirements coming from the large effective area and fast exposure period. At the same time, data transfer lines between components are redesigned in order to reduce the number and mass of the wire harnesses that limit the flexibility of the component distribution.
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Proceedings of SPIE - The International Society for Optical Engineering 5488(PART 2) 549-560 2004年 査読有り
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X-RAY TIMING 2003: ROSSI AND BEYOND 714 397-404 2004年Timing capabilities of the current and future X-ray astronomy satellites in Japan are reviewed. Stresses are put on the two programs, Astro-E2 and NeXT and some other programs are also mentioned. Astro-E2 is developed under the Japan-US collaboration, and is scheduled to be launched in February, 2005. Astro-E2 is basically a spectroscopic mission, and its timing capability of the focal-plane detectors is rather limited. However, the non-imaging, hard X-ray detector can provide a good time resolution. Astro-E2 will be followed by the NeXT satellite, which we plan to launch around 2010. NeXT is characterized by the direct imaging capability up to similar to80 keV. Its timing capability is also limited, but may be good for some kind of timing observations.
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PASJ : publications of the Astronomical Society of Japan 55(4) 827-840 2003年8月25日
所属学協会
4-
2000年1月 - 現在
共同研究・競争的資金等の研究課題
15-
日本学術振興会 科学研究費助成事業 基盤研究(C) 2019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 新学術領域研究(研究領域提案型) 2012年6月 - 2017年3月
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日本学術振興会 科学研究費助成事業 2012年4月 - 2015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) 2010年4月 - 2013年3月
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日本学術振興会 科学研究費助成事業 特別研究員奨励費 2005年 - 2007年
● 指導学生等の数
1-
年度2021年度(FY2021)修士課程学生数2連携大学院制度による学生数2学術特別研究員数1
● 専任大学名
1-
専任大学名総合研究大学院大学（SOKENDAI)
