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 教授
- J-GLOBAL ID
- 201801002962836691
- researchmap会員ID
- B000323419
- 外部リンク
主にX線天文学の研究をやっています。X線天体のフォローアップとして、地上赤外線観測、電波観測もやってます。ブラックホール、中性子星、白色矮星、AGN、銀河面からのX線放射などに興味を持っています。
宇宙航空研究開発機構（JAXA）・宇宙科学研究所（ISAS）にて、MAXI、XRISMを始めとする天文衛星のデータ処理・解析システムの開発、宇宙科学データアーカイブDARTSの運用を行っています。DARTSにおける全天多波長早見システムJUDO2を開発しました。また、「あかり」のアーカイブデータと他の衛星データを組み合わせ、LiteBIRDなどによる将来の宇宙論精密観測に必要な、銀河系内の赤外線前景放射モデルの作成に取り組んでいます。
研究キーワード
2研究分野
1経歴
4-
2005年8月 - 現在
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2001年8月 - 2004年12月
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1991年4月 - 1992年3月
学歴
2-
1986年4月 - 1991年3月
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1980年4月 - 1986年3月
委員歴
4-
2020年11月 - 現在
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2020年4月 - 現在
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2020年4月 - 現在
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2020年4月 - 現在
論文
330-
Astronomy and Astrophysics 2026年8月Context. The intracluster medium (ICM) is rich in chemical elements, produced by core-collapse (SNcc) and Type Ia supernovae (SNIa) over the last ∼12 Gyr. While cluster outskirts are uniformly enriched with Fe at ∼0.3 solar, strongly suggesting that the gas had been pre-enriched during or before the assembly of galaxies into clusters, the Fe abundance is known to centrally increase in the core of relaxed clusters. The origin of these central Fe peaks however, as well as the apparent presence of mysterious drops previously reported in the very centre of a number of systems, remain to be clarified. Aims. In this paper, we address these two questions by measuring the spatial distribution of Fe and its relative Si/Fe, S/Fe, Ar/Fe, Ca/Fe, Cr/Fe, Mn/Fe, and Ni/Fe ratios in the X-ray bright, nearby Perseus cluster. Methods. We take advantage of the unprecedented spectral resolution (∼5 eV) offered by the Resolve microcalorimeter on board XRISM, which observed four distinct pointings of Perseus out to ∼250 kpc (∼0.2r500) during its performance verification phase. Results. Although the presence of an X-ray bright AGN challenges a precise quantification of absolute abundances in the very core, our baseline analysis rules out a strong drop with > 2σ confidence, at variance with previous charge-coupled device (CCD) measurements. In addition, we find a remarkable spatial uniformity of X/Fe ratios, supporting the idea of negligible late SNIa enrichment from the brightest cluster galaxy NGC 1275. We also compare the overall chemical composition of the Perseus ICM with SNcc and SNIa nucleosynthesis yield models, finding that the co-existence of two separate SNIa enrichment channels is not needed to reproduce the ICM ratios satisfactorily....
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Geophysical Research Letters 2026年7月During the May 2024 super storm, we identified sub-second microburst-type relativistic electron precipitation events at McIlwain's $L\sim 2$ in low-Earth orbit using the Gamma-ray Burst Monitor (CGBM) onboard the CALorimetric Electron Telescope on the International Space Station. The high time resolution of CGBM (1/8 s) enables the detection of sub-MeV electron microbursts that are unresolved by most currently available radiation belt monitors, which typically lack sub-second cadence. Simultaneous plasma wave observations from the Arase satellite reveal enhanced whistler-mode chorus activity at Roederer's ${L}^{\ast }\sim 2$─4. These observations indicate that chorus-driven wave-particle interactions can operate at unusually low L-shells near the earthward-displaced inner edge of the outer radiation belt during extreme geomagnetic storms. Quantifying whether such chorus activity also contributes to local acceleration or slot filling requires future evaluation of wave properties, plasma conditions, diffusion coefficients, and acceleration and loss timescales....
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2026年7月Detection of primordial $B$-mode polarization in the cosmic microwave background (CMB) from tensor perturbations generated during inflation is a major scientific goal of future CMB missions. Its success will strongly depend on the characterization of polarized foregrounds, a challenge that the LiteBIRD satellite aims to tackle with its 15 frequency bands ranging from 40 to 402 GHz. In this work, we forecast the ability of LiteBIRD to characterize polarized dust and synchrotron emission in the diffuse interstellar medium (ISM), at the angular power spectrum level. From simulated LiteBIRD intensity and polarization maps with different foreground complexities, we compute cross-frequency angular power spectra and fit them to dust and synchrotron spectral energy distributions, which are modeled by a modified black body and a power law, respectively. We find that LiteBIRD will be able to measure the dust temperature, dust and synchrotron spectral indices and spatial correlation with dispersions as low as $σ(T_{\rm d})\sim0.2$ K, $σ(β_{\rm d})\sim0.006$, $σ(β_{\rm s})\sim0.04$ and $σ(ρ)\sim10^{-2}$, as well as to detect and quantify deviations from the proposed parametric model due to variations of the emission properties in the three dimensions of our Galaxy. Additionally, LiteBIRD is likely to rule out the power-law model of polarized foreground angular power spectra suggested by Planck data. It will also be able to detect differences in the values of $β_{\rm d}$, $T_{\rm d}$, and $β_{\rm s}$ between $E$ modes, $B$ modes, and intensity in the diffuse ISM for the first time, highlighting the joint variations of the physical conditions and the magnetic field structure across the Galaxy. We conclude that in addition to detailed studies of CMB polarization, LiteBIRD will open a new window onto the physical conditions governing the ISM of the Milky Way....
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2026年7月LiteBIRD is a JAXA-led space mission designed to produce all-sky microwave polarization maps. Its primary science goal is to test representative inflationary models by measuring the cosmic microwave background $B$-mode polarization generated by primordial gravitational waves, while also providing new insights into cosmology, particle physics, and astrophysics. The mission concept has been updated following the reformation activities initiated after the Mission Definition Review in 2024. The current concept preserves the central scientific objectives, while simplifying the payload configuration: a single telescope covers 12 frequency bands with band centers spanning 40 to 402~GHz, corresponding to an optical coverage of 34--448~GHz. The telescope is a cross-Dragone reflector with a 500~mm aperture diameter, cooled to approximately 5~K and coupled to transition-edge-sensor bolometer arrays operated at 0.1~K. LiteBIRD will observe from a Lissajous orbit around the Sun--Earth L2 point during a nominal 3-year survey. More specifically, the primary scientific objective is to achieve total uncertainty in the tensor-to-scalar ratio of $δr < 0.002$ (68\% C.L.), including contributions from foreground residuals, statistical uncertainties, instrumental systematics, and margin contingency. The corresponding map-noise requirements are specified separately for the low-, mid-, and high-frequency ranges over the reionization and recombination multipole ranges. This sensitivity makes LiteBIRD unique not only for inflationary science but also for a broad range of scientific investigations probing the history of both the early and late Universe, as well as for astrophysical processes, including Galactic science. This paper summarizes the scientific objectives, updated payload and instrument concepts, observation strategy, and ground segment plans....
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Publications of the Astronomical Society of Japan 2026年6月4日
MISC
129講演・口頭発表等
14-
JpGU-AGU Joint Meeting 2020:Virtual ユニオンセッション U-12 「地球惑星科学の進むべき道10 ビッグデータとオープンサイエンス」 2020年7月15日 招待有り
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20 Years of Chandra Science Symposium
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The 29th annual international Astronomical Data Analysis Software & Systems (ADASS)
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New eyes on X-ray astrophysical objects with Japanese and Chinese observatories 2018年11月21日 招待有り
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The 28th annual international Astronomical Data Analysis Software & Systems (ADASS) 2018年11月11日
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日本天文学会2018年秋季年会 天文教育フォーラム「市民との科学的活動を支えるオープンサイエンス」 2018年9月21日 招待有り
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The 42nd COSPAR Scientific Assembly 2018 2018年7月21日
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The 42nd COSPAR Scientific Assembly 2018 2018年7月18日
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PV2018 Conference - Adding value and preserving data 2018年5月15日
所属学協会
1共同研究・競争的資金等の研究課題
6-
日本学術振興会 科学研究費助成事業 2024年4月 - 2027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(C) 2016年4月 - 2019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(C) 2009年 - 2011年
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日本学術振興会 科学研究費助成事業 基盤研究(B) 2007年 - 2009年
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日本学術振興会 科学研究費助成事業 国際学術研究 1992年 - 1994年
