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 准教授
- 学位
- 博士(理学)(2004年3月 東京大学)
- 研究者番号
- 60446599
- ORCID ID
https://orcid.org/0000-0003-0441-7404- J-GLOBAL ID
- 202001021434500706
- researchmap会員ID
- R000012970
研究キーワード
6経歴
2-
2022年3月 - 現在
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2006年7月 - 2022年2月
学歴
3-
2001年4月 - 2004年3月
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1999年4月 - 2001年3月
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1995年4月 - 1999年3月
受賞
2論文
244-
NATURE 650(8101) 2026年2月12日 査読有り
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Journal of Astronomical Telescopes, Instruments, and Systems 12(01) 2026年1月28日 査読有り
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NATURE ASTRONOMY 10(1) 2026年1月 査読有り
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Journal of Astronomical Telescopes, Instruments, and Systems 11(04) 2025年12月18日 査読有り
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 77(6) 1278-1289 2025年12月 査読有り
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ASTROPHYSICAL JOURNAL LETTERS 994(1) 2025年11月20日 査読有り
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ASTROPHYSICAL JOURNAL LETTERS 993(1) 2025年11月1日 査読有り
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NATURE 646(8083) 2025年10月2日 査読有り
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JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS 11(4) 2025年10月1日 査読有り
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JOURNAL OF ASTRONOMICAL TELESCOPES INSTRUMENTS AND SYSTEMS 11(4) 2025年10月1日 査読有り
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ASTRONOMY & ASTROPHYSICS 702 2025年10月 査読有り
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Optics for EUV, X-Ray, and Gamma-Ray Astronomy XII 32-32 2025年9月18日
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UV, X-Ray, and Gamma-Ray Space Instrumentation for Astronomy XXIV 36-36 2025年9月18日
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ASTROPHYSICAL JOURNAL LETTERS 988(2) 2025年8月1日 査読有り
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Applied Radiation and Isotopes 222 111845-111845 2025年8月 査読有り
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The Astrophysical Journal Letters 988(1) L28-L28 2025年7月17日 査読有り
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Publications of the Astronomical Society of Japan 77(Supplement_1) S86-S95 2025年6月16日 査読有り
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Physical Review Letters 134(24) 2025年6月16日 査読有り
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ASTROPHYSICAL JOURNAL LETTERS 985(1) 2025年5月20日 査読有り
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Nature 641(8065) 1132-1136 2025年5月14日 査読有り
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npj Heritage Science 13(1) 2025年5月10日
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Publications of the Astronomical Society of Japan 77 S1-S9 2025年4月11日 査読有り
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The Astrophysical Journal Letters 982(1) L5-L5 2025年3月12日 査読有り
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Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1075 170362-170362 2025年3月 査読有り
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Nature 638(8050) 365-369 2025年2月12日 査読有り
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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
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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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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 査読有り
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 85-85 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 11(4) 235-235 2024年8月21日
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 92-92 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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Scientific Reports 14(1) 2024年2月9日 査読有りAbstract To detect and track structural changes in atomic nuclei, the systematic study of nuclear levels with firm spin-parity assignments is important. While linear polarization measurements have been applied to determine the electromagnetic character of gamma-ray transitions, the applicable range is strongly limited due to the low efficiency of the detection system. The multi-layer Cadmium-Telluride (CdTe) Compton camera can be a state-of-the-art gamma-ray polarimeter for nuclear spectroscopy with the high position sensitivity and the detection efficiency. We demonstrated the capability to operate this detector as a reliable gamma-ray polarimeter by using polarized 847-keV gamma rays produced by the $$^{56}\textrm{Fe}$$($${ p},{ p'}\gamma $$) reaction. By combining the experimental data and simulated calculations, the modulation curve for the gamma ray was successfully obtained. A remarkably high polarization sensitivity was achieved, compatible with a reasonable detection efficiency. Based on the obtained results, a possible future gamma-ray polarimetery is discussed.
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Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1059 169024-169024 2024年2月 査読有り
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Meteoritics and Planetary Science 2024年 査読有り
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IEEE Transactions on Radiation and Plasma Medical Sciences 7(8) 860-870 2023年11月 査読有り
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Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 1050 168175-168175 2023年5月 査読有り
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Physical Review Letters 130(17) 2023年4月27日 査読有り
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Physical Review Letters 130(11) 2023年3月15日 査読有り
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ACS Earth and Space Chemistry 7(4) 699-711 2023年3月9日 査読有り
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Journal of Instrumentation 18(01) P01030-P01030 2023年1月1日 査読有りAbstract We have developed a γ-ray computed tomography system using a CdTe double-sided strip detector. Owing to a 250 μm fine strip pitch and high energy resolution with photon-counting capability, the system provides highly accurate images, with which the materials and their distributions inside the target can be determined according to the photon transmittances. We evaluated the key performance of the system, conducting transmission measurements for Al, Cu, and Pb plates and also for Al, Fe, Cu, and Pb rod-phantoms, both using X-rays (∼30 keV) and γ-rays (∼80 keV) from a 133Ba source. The measured transmittances agreed well with the calculated values from simulations. We successfully reconstructed the three-dimensional structure of the rod-phantom and distinguished the elements inside the phantom. Compared with the simulated photon transmittances, we found that material identification based on tomographic images obtained with the system is efficient as long as the target object does not contain thick high-Z elements.
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Science 379(6634) 2022年9月22日 査読有りSamples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed seventeen Ryugu samples measuring 1-8 mm. CO 2 -bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu’s parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and Ca, Al-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed by aqueous alteration reactions at low temperature, high pH, and water/rock ratios < 1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate Ryugu’s parent body formed ~ 2 million years after the beginning of Solar System formation.
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RADIOISOTOPES 71(2) 141-151 2022年7月15日 査読有り
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IEEE Transactions on Radiation and Plasma Medical Sciences 6(5) 592-600 2022年5月 査読有り
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Nature Biomedical Engineering 6(5) 640-647 2022年4月4日 査読有り
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Scientific Reports 12(1) 2022年3月28日 査読有りAbstract Elemental analysis based on muonic X-rays resulting from muon irradiation provides information about bulk material composition without causing damage, which is essential in the case of precious or otherwise unreachable samples, such as in archeology and planetary science. We developed a three-dimensional (3D) elemental analysis technique by combining the elemental analysis method based on negative muons with an imaging cadmium telluride double-sided strip detector (CdTe-DSD) designed for the hard X-ray and soft $$\gamma$$-ray observation. A muon irradiation experiment using spherical plastic samples was conducted at the Japan Proton Accelerator Research Complex (J-PARC); a set of projection images was taken by the CdTe-DSD, equipped with a pinhole collimator, for different sample rotation angles. The projection images measured by the CdTe-DSD were utilized to obtain a 3D volumetric phantom by using the maximum likelihood expectation maximization algorithm. The reconstructed phantom successfully revealed the 3D distribution of carbon in the bulk samples and the stopping depth of the muons. This result demonstrated the feasibility of the proposed non-destructive 3D elemental analysis method for bulk material analysis based on muonic X-rays.
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Physical Review A 105(2) 2022年2月17日 査読有り
MISC
267講演・口頭発表等
124-
日本天文学会2025年春季年会 2025年3月19日
共同研究・競争的資金等の研究課題
18-
日本学術振興会 科学研究費助成事業 2025年4月 - 2029年3月
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日本学術振興会 科学研究費助成事業 2024年4月 - 2029年3月
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日本学術振興会 科学研究費助成事業 2025年4月 - 2028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(A) 2021年4月 - 2025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(A) 2020年4月 - 2024年3月
