Curriculum Vitaes
Profile Information
- Affiliation
- Professor, Department of Space Astronomy and Astrophysics, Institute of Space and Astronautical Science, Japan Aerospace Exploration AgencyProfessor, Space and Astronautical Science, Graduate Institute for Advanced Studies, The Graduate University for Advanced StudiesVisiting Professor, Department of Physics, School of Science, Institute of Science Tokyo
- Degree
- Ph. D.(The University of Tokyo)master's degree(The University of Tokyo)
- Researcher number
- 20280555
- ORCID ID
https://orcid.org/0000-0002-2374-7073- J-GLOBAL ID
- 200901095989600566
- researchmap Member ID
- 1000363020
I have been developing cryogenic high-resolution X-ray microcalorimeter spectrometers onboard X-ray astronomy satellite. It was achieved as the Resolve instrument onboard XRISM, which was launched in September, 2023.
Here are research themes I can provide. (1) Analyze high-resolution X-ray spectroscopy data obtained by XRISM satellite, and research motion of the hot gas in clusters of galaxies, in order to understand the formation of the large-scale structures of the Universe. (2) Conduct experimental studies, in anticipation of LiteBIRD mission, that aims for observing the polarization of the cosmic microwave background radiation.
Message to students: Through the research, develop an understanding of specific natural phenomena, and also learn the process to reach fundamental physics laws that underlie the complex phenomena, together with experimental and/or analytical methods.
Research Interests
4Research Areas
2Research History
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Apr, 1995 - Sep, 2003
Education
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Apr, 1991 - Mar, 1995
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Apr, 1987 - Mar, 1991
Committee Memberships
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Apr, 2009 - Mar, 2011
Papers
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Publications of the Astronomical Society of Japan, Apr 11, 2025Abstract 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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The Astrophysical Journal Letters, 982(1) L5-L5, Mar 12, 2025Abstract We present XRISM Resolve observations of the core of the hot, relaxed galaxy cluster Abell 2029 (A2029). We find that the line-of-sight bulk velocity of the intracluster medium (ICM) within the central 180 kpc is at rest with respect to the brightest cluster galaxy, with a 3σ upper limit of ∣v bulk∣ < 100 km s−1. We robustly measure the field-integrated ICM velocity dispersion to be σ v = 169 ± 10 km s−1, obtaining similar results for both single-temperature and two-temperature plasma models to account for the cluster cool core. This result, if ascribed to isotropic turbulence, implies a subsonic ICM with Mach number and a nonthermal pressure fraction of 2.6 ± 0.3%. The turbulent velocity is similar to what was measured in the core of the Perseus cluster by Hitomi, but here in a more massive cluster with an ICM temperature of 7 keV, the limit on the nonthermal pressure fraction is even more stringent. Our result is consistent with expectations from simulations of relaxed clusters, but it is on the low end of the predicted distribution, indicating that A2029 is an exceptionally relaxed cluster with no significant impacts from either a recent minor merger or active galactic nucleus activity.
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Nature, 638(8050) 365-369, Feb 12, 2025
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Publications of the Astronomical Society of Japan, Dec 26, 2024Abstract Sagittarius A East is a supernova remnant with a unique surrounding environment, as it is located in the immediate vicinity of the supermassive black hole at the Galactic center, Sagittarius A$^{*}$. The X-ray emission of the remnant is suspected to show features of overionized plasma, which would require peculiar evolutionary paths. We report on the first observation of Sagittarius A East with the X-Ray Imaging and Spectroscopy Mission (XRISM). Equipped with a combination of a high-resolution microcalorimeter spectrometer and a large field-of-view CCD imager, we for the first time resolved the Fe xxv K-shell lines into fine structure lines and measured the forbidden-to-resonance intensity ratio to be $1.39 \pm 0.12$, which strongly suggests the presence of overionized plasma. We obtained a reliable constraint on the ionization temperature just before the transition into the overionization state, of $\gt\! 4\:$keV. The recombination timescale was constrained to be $\lt\! 8 \times 10^{11} \:$cm$^{-3}\:$s. The small velocity dispersion of $109 \pm 6\:$km$\:$s$^{-1}$ indicates a low Fe ion temperature $\lt\! 8\:$keV and a small expansion velocity $\lt\! 200\:$km$\:$s$^{-1}$. The high initial ionization temperature and small recombination timescale suggest that either rapid cooling of the plasma via adiabatic expansion from dense circumstellar material or intense photoionization by Sagittarius A$^{*}$ in the past may have triggered the overionization.
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The Astrophysical Journal Letters, 977(2) L34-L34, Dec 11, 2024Abstract 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.
Misc.
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日本物理学会講演概要集(CD-ROM), 79(1), 2024
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日本物理学会講演概要集(CD-ROM), 78(2), 2023
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日本物理学会講演概要集(CD-ROM), 77(1), 2022
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日本物理学会講演概要集(CD-ROM), 77(2), 2022
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日本物理学会講演概要集(CD-ROM), 76(2), 2021
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日本物理学会講演概要集(CD-ROM), 75(1), 2020
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Publications of the Astronomical Society of Japan, 70(6), 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Publications of the Astronomical Society of Japan, 70(2), 2018
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Proceedings of SPIE - The International Society for Optical Engineering, 10397, 2017 Peer-reviewed
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Proceedings of SPIE - The International Society for Optical Engineering, 10397, 2017 Peer-reviewed
Professional Memberships
2Research Projects
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科学研究費助成事業 基盤研究(C), 日本学術振興会, Apr, 2023 - Mar, 2026
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科学研究費助成事業 新学術領域研究(研究領域提案型), 日本学術振興会, Apr, 2019 - Mar, 2021
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (A), Japan Society for the Promotion of Science, Apr, 2013 - Mar, 2017
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Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, Apr, 2011 - Mar, 2014
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科研費 挑戦的萌芽研究, Apr, 2008 - Mar, 2011
