Curriculum Vitaes
Profile Information
- Affiliation
- Professor, Graduate School of Science and Engineering, Saitama UniversitySpecially Appointed Professor, Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency
- Degree
- Master (Science)(the University of Tokyo)Dr. (Science)(the University of Tokyo)
- J-GLOBAL ID
- 200901083726265608
- researchmap Member ID
- 1000161587
- External link
Research Interests
14Research History
4-
Apr, 2007 - Present
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Sep, 2000 - Mar, 2007
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Apr, 1993 - Aug, 2000
Education
3-
Apr, 1990 - Mar, 1993
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Apr, 1987 - Mar, 1990
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- Mar, 1988
Committee Memberships
2-
Nov, 2020 - Present
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Jan, 2009 - May, 2013
Awards
2-
2007
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1999
Papers
203-
NATURE, 646(8083), Oct 2, 2025
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Publications of the Astronomical Society of Japan, Sep 30, 2025 Peer-reviewed
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ASTROPHYSICAL JOURNAL LETTERS, 988(2), Aug 1, 2025
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ASTROPHYSICAL JOURNAL LETTERS, 988(2), Aug 1, 2025
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ASTROPHYSICAL JOURNAL LETTERS, 988(1), Jul 20, 2025
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN, Jul 8, 2025
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JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS, 11(3), Jul 1, 2025
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NATURE, 641(8065), May 29, 2025
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ASTROPHYSICAL JOURNAL LETTERS, 985(1), May 20, 2025
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN, May 14, 2025
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Publications of the Astronomical Society of Japan, Apr 11, 2025 Peer-reviewedLead authorCorresponding authorAbstract The X-Ray Imaging and Spectroscopy Mission (XRISM) is a joint mission between the Japan Aerospace Exploration Agency (JAXA) and the National Aeronautics and Space Administration (NASA) in collaboration with the European Space Agency (ESA). In addition to the three space agencies, universities and research institutes from Japan, North America, and Europe have joined to contribute to developing satellite and onboard instruments, data-processing software, and the scientific observation program. XRISM is the successor to the ASTRO-H (Hitomi) mission, which ended prematurely in 2016. Its primary science goal is to examine astrophysical problems with precise, high-resolution X-ray spectroscopy. XRISM promises to discover new horizons in X-ray astronomy. It carries a 6 × 6 pixelized X-ray microcalorimeter on the focal plane of an X-ray mirror assembly (Resolve) and a co-aligned X-ray CCD camera (Xtend) that covers the same energy band over a large field of view. XRISM utilizes the Hitomi heritage, but all designs were reviewed. The attitude and orbit control system was improved in hardware and software. The spacecraft was launched from the JAXA Tanegashima Space Center on 2023 September 6 (UTC). During the in-orbit commissioning phase, the onboard components were activated. Although the gate valve protecting the Resolve sensor with a thin beryllium X-ray entrance window was not yet opened, scientific observation started in 2024 February with the planned performance verification observation program. The nominal observation program commenced with the following guest observation program beginning in 2024 September.
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ASTROPHYSICAL JOURNAL LETTERS, 982(1), Mar 20, 2025
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Nature, 638(8050) 365-369, Feb 12, 2025 Peer-reviewed
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Publications of the Astronomical Society of Japan, 77(1) L1-L8, Dec 26, 2024 Peer-reviewed
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The Astrophysical Journal Letters, 977(2) L34-L34, Dec 11, 2024 Peer-reviewedAbstract The X-ray binary system Cygnus X-3 (4U 2030+40, V1521 Cyg) is luminous but enigmatic owing to the high intervening absorption. High-resolution X-ray spectroscopy uniquely probes the dynamics of the photoionized gas in the system. In this Letter, we report on an observation of Cyg X-3 with the XRISM/Resolve spectrometer, which provides unprecedented spectral resolution and sensitivity in the 2–10 keV band. We detect multiple kinematic and ionization components in absorption and emission whose superposition leads to complex line profiles, including strong P Cygni profiles on resonance lines. The prominent Fe xxv Heα and Fe xxvi Lyα emission complexes are clearly resolved into their characteristic fine-structure transitions. Self-consistent photoionization modeling allows us to disentangle the absorption and emission components and measure the Doppler velocity of these components as a function of binary orbital phase. We find a significantly higher velocity amplitude for the emission lines than for the absorption lines. The absorption lines generally appear blueshifted by ∼−500–600 km s−1. We show that the wind decomposes naturally into a relatively smooth and large-scale component, perhaps associated with the background wind itself, plus a turbulent, denser structure located close to the compact object in its orbit.
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Geophysical Research Letters, 51(20), Oct 26, 2024 Peer-reviewedAbstract We present X‐ray observations of the upper atmospheric density disturbance caused by the explosive eruption of the Hunga Tonga‐Hunga Ha'apai (HTHH) volcano on 15 January 2022. From 14 January to 16 January, the Chinese X‐ray astronomy satellite, Insight‐HXMT, was observing the supernova remnant Cassiopeia A. The X‐ray data obtained during Earth's atmospheric occultations allowed us to measure neutral densities in the altitude range of 90–150 km. The density profiles above 110 km altitude obtained before the major eruption are in reasonable agreement with expectations by both GAIA and NRLMSIS 2.0 models. In contrast, after the HTHH eruption, a severe density depletion was found up to 1,000 km away from the epicenter, and a relatively weak depletion extending up to km for over 8 hr after the eruption. In addition, density profiles showed wavy structures with a typical length scale of either 20 km (vertical) or 1,000 km (horizontal). This may be caused by Lamb waves or gravity waves triggered by the volcanic eruption.
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Publications of the Astronomical Society of Japan, 76(6) 1186-1201, Oct 10, 2024 Peer-reviewedAbstract 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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Astrophysical Journal Letters, 973(1), Sep 1, 2024 Peer-reviewed
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 13093 224-224, Aug 21, 2024
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 235-235, Aug 21, 2024
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 13093 61-61, Aug 21, 2024
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 13093 60-60, Aug 21, 2024
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray, 13093 52-52, Aug 21, 2024 Lead authorCorresponding author
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The Astrophysical Journal, Aug 1, 2023 Peer-reviewed
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Journal of Geophysical Research: Space Physics, 128(2), Feb 21, 2023 Peer-reviewed
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Nature Astronomy, 6(12) 1364-1375, Dec 12, 2022 Peer-reviewed
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Nature Astronomy, 7(1) 80-87, Dec 8, 2022 Peer-reviewed
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Journal of Low Temperature Physics, 209(5-6) 1088-1096, Sep 19, 2022 Peer-reviewed
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Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray, Aug 31, 2022 Peer-reviewed
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Publications of the Astronomical Society of Japan, Jun 2, 2022 Peer-reviewed
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Monthly Notices of the Royal Astronomical Society, 512(4) 5995-6006, Apr 19, 2022 Peer-reviewedAbstract The far infrared counterpart of hot spot D, the terminal hot spot of the eastern jet hosted by the radio galaxy Cygnus A, is detected with Herschel Aperture photometery of the source performed in 5 photometric bands covering the wavelength range of 70–350 μm. After removing the contamination from another nearby hot spot, E, the far-infrared intensity of hot spot D is derived as 83 ± 13 and 269 ± 66 mJy at 160 and 350 μm, respectively. Since the far-infrared spectrum of the object smoothly connects to the radio one, the far-infrared emission is attributed to the synchrotron radiation from the radio-emitting electron population. The radio-to-near-infrared spectrum is confirmed to exhibit a far-infrared break feature at the frequency of $\nu _\mathrm{br}=2.0^{+1.2}_{-0.8} \times 10^{12}$ Hz. The change in energy index at the break (Δα = 0.5) is interpreted as the impact of radiative cooling on an electron distribution sustained by continuous injection from diffusive shock acceleration. By ascribing the derived break to this cooling break, the magnetic field, B, in the hot spot is determined as a function of its radius, R within a uniform one-zone model combined with the strong relativistic shock condition. An independent B-R constraint is obtained by assuming the X-ray spectrum is wholly due to synchrotron-self-Compton emission. By combining these conditions, the two parameters are tightly determined as B = 120–150 μG and R = 1.3–1.6 kpc. A further investigation into the two conditions indicates the observed X-ray flux is highly dominated by the synchrotron-self-Compton emission.
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International Journal of Modern Physics D,, 31(2) id 2230001, Jan, 2022 Peer-reviewedInvitedLead author
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Journal of Astronomical Telescopes, Instruments, and Systems, 7(03), Jul 1, 2021 Peer-reviewed
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Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray, Dec 13, 2020
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Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray, Dec 13, 2020 Lead authorCorresponding author
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Journal of Geophysical Research: Space Physics, 126(4), Nov 24, 2020 Peer-reviewed
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The Astrophysical Journal, 899(1) 17-17, Aug 1, 2020 Peer-reviewed
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The Astrophysical Journal, 891(2) 126-126, Mar 10, 2020 Peer-reviewed
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The Astrophysical Journal, 889(2), Feb 1, 2020
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Proceedings of the International Astronomical Union, 29-36, 2020
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Proceedings of SPIE - The International Society for Optical Engineering, 11444, 2020
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Proceedings of SPIE - The International Society for Optical Engineering, 11444, 2020
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The Astrophysical Journal, 884(2) L58-L58, Oct 21, 2019 Peer-reviewed
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Publications of the Astronomical Society of Japan, 71(4), Aug 1, 2019
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Journal of Low Temperature Physics, 1-7, Mar 8, 2018 Peer-reviewed
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Journal of Astronomical Telescopes, Instruments, and Systems, 4(1), Jan 1, 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018 Peer-reviewed
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Journal of Astronomical Telescopes, Instruments, and Systems, 4(1) 011218, Jan 1, 2018 Peer-reviewed
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JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS, 4(1), Jan, 2018 Peer-reviewed
Misc.
289Presentations
101-
MAXI 15 Year Workshop for the Time Domain Astronomy, Dec 10, 2024 Invited
Teaching Experience
67Professional Memberships
2-
1987 - Present
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1987 - Present
Research Projects
16-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Jul, 2020 - Mar, 2023
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2015 - Mar, 2018
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2010 - Mar, 2015
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科学研究費助成事業, 日本学術振興会, 2008 - 2008
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Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, 2006 - 2008