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 宇宙航空プロジェクト研究員(兼任)宇宙科学研究所 X線分光撮像衛星(XRISM)プロジェクトチーム 宇宙航空プロジェクト研究員
- 研究者番号
- 51003595
- ORCID ID
https://orcid.org/0000-0001-8055-7113- J-GLOBAL ID
- 202401002152895362
- Researcher ID
- JPK-5103-2023
- researchmap会員ID
- R000066682
経歴
1論文
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The Astrophysical Journal Letters 985(1) L20-L20 2025年5月19日 査読有りAbstract The XRISM Resolve microcalorimeter array measured the velocities of hot intracluster gas at two positions in the Coma galaxy cluster: squares at the center and at 6 (170 kpc) to the south. We find the line-of-sight velocity dispersions in those regions to be σ z = 208 ± 12 km s−1 and 202 ± 24 km s−1, respectively. The central value corresponds to a 3D Mach number of M = 0.24 ± 0.015 and a ratio of the kinetic pressure of small-scale motions to thermal pressure in the intracluster plasma of only 3.1% ± 0.4%, at the lower end of predictions from cosmological simulations for merging clusters like Coma, and similar to that observed in the cool core of the relaxed cluster A2029. Meanwhile, the gas in both regions exhibits high line-of-sight velocity differences from the mean velocity of the cluster galaxies, Δv z = 450 ± 15 km s−1 and 730 ± 30 km s−1, respectively. A small contribution from an additional gas velocity component, consistent with the cluster optical mean, is detected along a sight line near the cluster center. The combination of the observed velocity dispersions and bulk velocities is not described by a Kolmogorov velocity power spectrum of steady-state turbulence; instead, the data imply a much steeper effective slope (i.e., relatively more power at larger linear scales). This may indicate either a very large dissipation scale, resulting in the suppression of small-scale motions, or a transient dynamic state of the cluster, where large-scale gas flows generated by an ongoing merger have not yet cascaded down to small scales.
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Nature 641(8065) 1132-1136 2025年5月14日 査読有り
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2025年5月XRISM/Xtend Transient Search (XTS) detected multiple X-ray flares from the X-ray source XRISM J0535-6613 on 2025-05-25 and 05-26 TT. The source position is (R.A., Dec.) = (83.827, -66.218), with a systematic error of & sim; 40 arcsec....
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2025年5月XRISM/Xtend Transient Search (XTS) detected an X-ray brightening from an X-ray source XRISM J0918-1212 on 2025-05-06 TT. The source position is determined to be (R.A., Dec.) = (139.395, -12.200), with a systematic error of & sim; 40 arcsec....
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Publications of the Astronomical Society of Japan 2025年4月11日 査読有りAbstract 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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2025年4月XRISM/Xtend Transient Search (XTS) detected an X-ray outburst from an X-ray source XRISM J1826-3651 on 2025-04-12 TT. The source position is determined to be (R.A., Dec.) = (276.543, -36.849), with a systematic error of ~40 arcsec....
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2025年4月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1712-2310 on 2025-04-05 TT. The source position is determined to be (R.A., Dec.) = (258.042, -23.162), with a systematic error of & sim; 40 arcsec....
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2025年4月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1746-2940 on 2025-04-12 TT. The source position is determined to be (R.A., Dec.) = (266.528, -29.671), with a systematic error of ~ 40 arcsec....
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The Astrophysical Journal Letters 982(1) L5-L5 2025年3月12日 査読有りAbstract 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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2025年3月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source, XRISM J1911+0509, on 2025-03-27 TT. The source position is determined to be (R.A., Dec.) = (287.733, 5.150), with a systematic error of & sim; 40 arcsec....
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2025年3月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1733-2440 on 2025-03-25 TT. The source position is determined to be (R.A., Dec.) = (263.262, -24.588), with a systematic error of & sim; 40 arcsec....
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2025年3月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1747-2832 located at the Galactic central region on 2025-03-19 TT. The source position is determined to be (R.A., Dec.) = (266.761, -28.538), with a systematic error of & sim; 40 arcsec....
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2025年3月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1748-2832 on 2025-03-09 TT. The source position is determined to be (R.A., Dec.) = (266.890 -28.538), with a systematic error of & sim; 40 arcsec....
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2025年3月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1718-3711 on 2025-03-06 TT. The source position is determined to be (R.A., Dec.) = (259.375, -37.183), with a systematic error of & sim; 40 arcsec....
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2025年3月A follow-up XRISM observation has been performed for the new Galactic centre transient MAXI J1744-294 detected by MAXI on January 2, 2025 (ATels #16975 and #16983)....
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2025年3月XRISM/Xtend Transient Search (XTS) detected an increase in X-ray intensity from an X-ray source XRISM J1717-3717 on 2025-02-28 TT. The source position is determined to be (R.A., Dec.) = (259.347, -37.28648), with a systematic error of & sim; 40 arcsec....
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Nature 638(8050) 365-369 2025年2月12日 査読有り
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2025年2月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J0604+4209 on 2025-02-23 TT. The source position is determined to be (R.A., Dec.) = (90.974, 42.144), with a systematic error of & sim; 40 arcsec....
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2025年1月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1349+2659 on 2025-01-21 TT. The source position is determined to be (R.A., Dec.) = (207.270, 26.975), with a systematic error of & sim; 40 arcsec....
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Publications of the Astronomical Society of Japan 77(1) L1-L8 2024年12月26日 査読有りAbstract 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 2024年12月11日 査読有りAbstract 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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2024年12月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J0057+6021 on 2024-12-29 TT. The source position is determined to be (R.A., Dec.) = (14.195, 60.356), with a systematic error of & #8764; 40 arcsec....
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2024年11月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1226+3347 on 2024-11-10 TT. The source position is determined to be (R.A., Dec.) = (186.488, 33.781), with a systematic error of & sim; 40 arcsec....
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Publications of the Astronomical Society of Japan 76(6) 1186-1201 2024年10月10日 査読有り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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The Astrophysical Journal Letters 973(1) L25-L25 2024年9月1日 査読有り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 61-61 2024年8月21日
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 60-60 2024年8月21日
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 235-235 2024年8月21日
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 236-236 2024年8月21日
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 224-224 2024年8月21日
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 52-52 2024年8月21日
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2024年8月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1137-6516 on 2024-08-13 TT. The source position is determined to be (R.A., Dec.) = (174.244, -65.273), with a systematic error of & ndash; 40 arcsec....
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2024年8月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1142-6522 on 2024-08-13 TT. The source position is determined to be (R.A., Dec.) = (175.418, -65.363), with a systematic error of & ndash; 40 arcsec....
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2024年8月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from the X-ray source XRISM J1142-6522, whose possible counterpart is 2MASS J11414215-6521298 at 101 pc, on 2024-08-14 TT. This is the second report by XRISM of a brightening of this source following the last one (ATel #16774)....
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2024年8月XRISM/Xtend Transient Search (XTS) detected X-ray flares from the X-ray source XRISM J1142-6522, whose possible counterpart is 2MASS J11414215-6521298 at 101 pc, on 2024-08-15 TT. We report the largest flare in this period although the activity is continued....
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2024年8月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1140-6519 on 2024-08-17 TT. The source position is determined to be (R.A., Dec.) = (175.081, -65.316), with a systematic error of & sim; 40 arcsec....
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2024年8月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1745-2914 on 2024-08-29 TT. The source position is determined to be (R.A., Dec.) = (266.276, -29.246), with a systematic error of & sim; 40 arcsec....
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2024年7月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from the X-ray source XRISM J1558+2534, whose plausible counterpart is MS Ser, on 2024-07-02 TT. This is the second flare of this source during the XRISM observation of T CrB (ATel #16683)....
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2024年7月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1558+2534 on 2024-07-01 TT. The source position is determined to be (R.A., Dec.) = (239.679 deg, +25.573 deg), with systematic error of & sim; 40 arcsec....
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2024年7月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1138-3742 on 2024-07-19 TT. The source position is determined to be (R.A., Dec.) = (174.415 deg, -37.707 deg), with a systematic error of -40 arcsec....
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2024年7月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source XRISM J1138-3742, whose plausible counterpart is UCAC2 15735923, on 2024-07-21....
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Astronomy & Astrophysics 686 A96-A96 2024年6月3日 査読有り筆頭著者責任著者Context. The interstellar medium (ISM) in starburst galaxies contains many chemical elements that are synthesised by core-collapse supernova explosions. By measuring the abundances of these metals, we can study the chemical enrichment within the galaxies and the transportation of metals into the circumgalactic environment through powerful outflows. Aims. We performed a spectral analysis of the X-ray emissions from the core of M 82 using the Reflection Grating Spectrometer (RGS) on board XMM-Newton to accurately estimate the metal abundances in the ISM. Methods. We analysed over 300 ks of RGS data observed with 14 position angles, covering a cross-dispersion width of 80 arcsec. We employed multi-temperature thermal plasma components in collisional ionisation equilibrium (CIE) to reproduce the observed spectra, each of which exhibited a different spatial broadening. Results. The O VII band CCD image shows a broader distribution that those for the O VIII and Fe-L bands. The O VIII line profiles have a prominent double-peaked structure that corresponds to the north- and southward outflows. The O VII triplet feature exhibits marginal peaks. A single CIE component that is convolved with the O VII band image approximately reproduces the spectral shape. A CIE model combined with a charge-exchange emission model also successfully reproduces the O VII line profiles. However, the ratio of these two components varies significantly with the observed position angles, which is physically implausible. Spectral fitting of the broadband spectra suggests a multi-temperature phase in the ISM that is approximated by three components at 0.1, 0.4, and 0.7 keV. Notably, the 0.1 keV component exhibits a broader distribution than the 0.4 and 0.7 keV plasmas. The derived abundance pattern shows super-solar N/O, solar Ne/O and Mg/O, and half-solar Fe/O ratios. These results indicate the chemical enrichment by core-collapse supernovae in starburst galaxies.
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2024年6月XRISM/Xtend Transient Search (XTS) detected an X-ray flare from an X-ray source candidate XRISM J1045-5954 on 2024-06-10 TT in the direction of the Carina Nebula....
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2024年5月XRISM/Xtend Transient Search (XTS) detected an X-ray outburst from a high-mass X-ray binary AX J1910.7+0917 on 2024-04-28 TT. Due to a bad time interval of XRISM, the outburst start time was not detected, but only a rough constraint, 2024-04-28 19:52 & ndash; 20:41 TT, is given....
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2024年5月XRISM team detected SN2024iss with Xtend during the ToO observation from 2024-05-24 16:56 TT to 2024-05-25 16:54 TT aimed at (RA, DEC) = (12h 59m 06s, 28d 48m 36s)....
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Publications of the Astronomical Society of Japan 75(6) 1324-1336 2023年12月1日 査読有り
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Astrophysical Journal 953(1) 2023年8月1日 査読有り筆頭著者責任著者
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Publications of the Astronomical Society of Japan 74(6) 1396-1414 2022年12月1日 査読有り
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Monthly Notices of the Royal Astronomical Society 514(3) 4222-4238 2022年8月1日 査読有り筆頭著者責任著者
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Astrophysical Journal 897(1) 2020年7月1日 査読有り筆頭著者責任著者
共同研究・競争的資金等の研究課題
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日本学術振興会 科学研究費助成事業 2023年3月 - 2024年3月
