Profile Information
- Affiliation
- Professor, Institute of Space and Astronautical Science, Japan Aerospace Exploration AgencyGraduate School of Science, Department of Physics, The University of Tokyo(PI), International Center for Quantum-field Measurement Systems for Studies of the Universe and Particles (QUP)Graduate School of Science, Kitasato University
- Degree
- Ph. D.(Mar, 1996, The University of Tokyo)
- ORCID ID
https://orcid.org/0000-0003-4885-5537- J-GLOBAL ID
- 200901003330670433
- Researcher ID
- C-2252-2008
- researchmap Member ID
- 5000019022
- External link
Research Interests
8Research Areas
2Research History
2Education
2-
Apr, 1989 - Mar, 1993
-
Apr, 1985 - Mar, 1989
Committee Memberships
2-
Oct, 2017 - Sep, 2023
-
Oct, 2014 - Sep, 2017
Papers
257-
IEEE Transactions on Applied Superconductivity, 35(5) 1-4, Aug, 2025 Peer-reviewed
-
The Astrophysical Journal Letters, 982(1) L5-L5, Mar 12, 2025 Peer-reviewedAbstract 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.
-
Nature, 638(8050) 365-369, Feb 12, 2025 Peer-reviewed
-
Publications of the Astronomical Society of Japan, 77(1) L1-L8, Dec 26, 2024 Peer-reviewedAbstract 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.
-
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.
Misc.
189-
Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave, Dec 21, 2020
-
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, Dec 16, 2020
-
Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy X, Dec 16, 2020
Teaching Experience
1-
Mar, 2003 - PresentAstrophysics I (Dept. of Physics, University. of Tokyo)
Professional Memberships
3-
2010 - Present
Research Projects
22-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Nov, 2020 - Mar, 2025
-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Nov, 2020 - Mar, 2025
-
科学研究費助成事業 基盤研究(A), 日本学術振興会, Apr, 2019 - Mar, 2022
-
Grants-in-Aid for Scientific Research, Japan Society for the Promotion of Science, Apr, 2018 - Mar, 2022
-
Grants-in-Aid for Scientific Research Grant-in-Aid for Scientific Research (B), Japan Society for the Promotion of Science, Apr, 2018 - Mar, 2021
教育内容やその他の工夫
1-
SubjcetGraduate School in ISASSummaryWe accept graduate students from University of Tokyo and Kitasato University. Our main scope is observational research of the large scale structure in the Universe utilizing X-ray spectroscopy.
During the graduate school, professional education for development of new detectors and their applications, and observational astrophysics are accessed.
● 指導学生等の数
8-
Fiscal Year2018年度(FY2018)Doctoral program1Master’s program1
-
Fiscal Year2019年度(FY2019)Doctoral program1Master’s program3
-
Fiscal Year2020年度(FY2020)Doctoral program1Master’s program3
-
Fiscal Year2018年度(FY2018)Doctoral program1Master’s program1
-
Fiscal Year2019年度(FY2019)Doctoral program1Master’s program3
-
Fiscal Year2020年度(FY2020)Doctoral program1Master’s program3
-
Fiscal Year2022年度(FY2022)Doctoral program3Master’s program2
-
Fiscal Year2023年度(FY2023)Doctoral program2Master’s program1
● 指導学生の顕著な論文
6-
Student nameRyota TakakuStudent affiliation東京大学Author(s), journal, volume number, pagination (year of publication)Takaku et al. , Journal of Applied Physics, 128(22), id.225302, (2020)TitleBroadband, millimeter-wave anti-reflective structures on sapphire ablatedwith femto-second laserDOIhttp://doi.org/10.1063/5.0022765
-
Student nameYuki NakashimaStudent affiliationUniv. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Nakashima et al. Applied Physics Letters, 117 122601 (2020)TitleLow-noise microwave SQUID multiplexed readout of 38 x-ray transition-edge sensor microcalorimetersDOIhttp://doi.org/10.1063/5.0016333
-
Student nameRyohei KonnoStudent affiliationKitasato Univ.Author(s), journal, volume number, pagination (year of publication)Konno et al. Journal of Low Temperature Physics 199, 654 (2019)TitleDevelopment of TES micsrocalorimters with solar-axion converterDOIhttp://doi.org/10.1007/s10909-019-02257-9
-
Student nameRyo YamamotoStudent affiliationUniv. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Yamamoto et al. , Journal of Cosmokogy and Astrophysics, 02 (2020) 011TitleA Search for a Contribution from Axion-Like Particles to the X-Ray Diffuse Background Utilizing the Earth's Magnetic FieldDOIhttp://doi.org/10.1088/1475-7516/2020/02/011
-
Student nameNorio SekiyaStudent affiliationUniversity. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Sekiya, Yamasaki, and Mitsuda, Publications of Astronomical Society in Japan, 68(SP1), S31 (2016)TitleSearch for a keV Signature of Radiatively Decaying Dark Matter with Suzaku XIS Observations of the X-ray Diffuse BackgroundDOIhttp://doi.org/10.1093/pasj/psv081
-
Student nameIkuyuki MitsuishiStudent affiliationUniv. of TokyoAuthor(s), journal, volume number, pagination (year of publication)Mitsuishi, Yamasaki, and Takei, Publications of Astronomical Society in Japan, 65, 44 (2013)TitleAn X-Ray Study of the Galactic-Scale Starburst-Driven Outflow in NGC 253DOIhttp://doi.org/10.1093/pasj/65.2.44
● 専任大学名
1-
Affiliation (university)東京大学（University of Tokyo)
● 所属する所内委員会
1-
ISAS CommitteeSteering committee for ISAS nono-electronics clean room
