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 助教
- 学位
- 博士(理学)(2002年3月 東京大学理学系研究科物理学専攻)
- J-GLOBAL ID
- 202001017082346100
- researchmap会員ID
- R000012159
経歴
11-
2024年4月 - 現在
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2019年4月 - 現在
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2018年4月 - 2019年3月
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2017年4月 - 2018年3月
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2016年4月 - 2017年3月
学歴
2-
1999年4月 - 2002年3月
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1997年4月 - 1999年3月
受賞
2主要な論文
119-
The Astrophysical Journal 2023年8月1日 査読有り筆頭著者
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Monthly Notices of the Royal Astronomical Society 512(4) 5995-6006 2022年3月25日 査読有り
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The Astrophysical Journal 899(1) 17-17 2020年8月7日 査読有り筆頭著者
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The Astrophysical Journal 850(2) 193-193 2017年12月1日 査読有り筆頭著者
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 68(6) 2016年12月
MISC
57-
VizieR On-line Data Catalog 2023年10月
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Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave 2020年12月13日
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Space Telescopes and Instrumentation 2018: Optical, Infrared, and Millimeter Wave 2018年7月12日
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Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray 10699 2018年7月6日
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Space Telescopes and Instrumentation 2018: Ultraviolet to Gamma Ray 2018年7月6日
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宇宙航空研究開発機構特別資料 = JAXA Special Publication: The Cosmic Wheel and the Legacy of the AKARI archive: from galaxies and stars to planets and life (17) 217-220 2018年3月9日第4回「あかり」国際会議 (2017年10月17-20日. 東京大学), 文京区, 東京形態: カラー図版あり資料番号: AA1730026036レポート番号: JAXA-SP-17-009E The 4th AKARI International Conference: The Cosmic Wheel and the Legacy of the AKARI archive: from galaxies and stars to planets and life (October 17-20, 2017. The University of Tokyo), Bunkyo-ku, Tokyo, JapanWe analyzed the 4.67 micrometers CO ro-vibrational absorption band in nearby ten active galactic nuclei (AGNs) observed with AKARI and Spitzer by fitting a plane-parallel local thermal equilibrium gas model. We found that the CO gas is warm (200-500 K) with a large column density (N(sub H) less than in the order of 10(exp 23) cm-2). Such a large column of warm gas is not achievable with UV heating or shock heating in starbursts. The most convincing heating source is X-ray photons emitted from the nuclei, which can produce warm gas of N(sub H) in the order of 10(exp 24) cm-2. This indicates that the region probed by the CO absorption is in the vicinity of the nuclei. The hydrogen column density estimated from the CO band is smaller than that inferred from X-ray observations. The observed deep absorption implies that the gas is close to the continuum source. We suggest that the probed region is outside the X-ray emitting region and just in front of the dust sublimation layer, which can be designated as the inner rim of the obscuring material around the AGNs.Physical characteristics: Original contains color illustrations
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宇宙航空研究開発機構特別資料 = JAXA Special Publication: Proceedings of the SPICA Science Conference from Exoplanets to Distant Galaxies: SPICA's New Window on the Cool Universe (17) 117-119 2018年3月9日形態: カラー図版あり資料番号: AA1730027026レポート番号: JAXA-SP-17-010E SPICA Science Conference from Exoplanets to Distant Galaxies: SPICA's New Window on the Cool Universe (June 18-21, 2013. Ito Hall, the University of Tokyo), Bunkyou-ku, Tokyo, JapanWe carried out systematic observations of the HI recombination line Bra (4.05 μm) in nearby (z less than 0.3) ultraluminous infrared galaxies (ULIRGs), using AKARI near-infrared 2.5-5.0 μm spectroscopy. We derived star formation rates (SFRs) from the Bra line, whose observed flux is predicted to be the highest among HI recombination lines in conditions with large dust extinction (visual extinction Av greater than 15 mag) expected in ULIRGs. Using the 3.3 μm polycyclic aromatic hydrocarbon emission in addition to the Bra line as an indicator of the SFR, we estimated the contribution of the star formation to the total infrared luminosity in 51 ULIRGs. The contribution was on average 28 plus or minus4 0/o in ULIRGs optically classified as H II, while 14 plus or minus2 0/o in ULIRGs optically classified as LINER or Seyfert. This result indicates that the star formation is significantly active in H II ULIRGs and other energy source, i.e. active galactic nuclei, is needed in LINER ULIRGs.Physical characteristics: Original contains color illustrations
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宇宙航空研究開発機構特別資料 = JAXA Special Publication: The Cosmic Wheel and the Legacy of the AKARI archive: from galaxies and stars to planets and life (17) 379-382 2018年3月9日第4回「あかり」国際会議 (2017年10月17-20日. 東京大学), 文京区, 東京形態: カラー図版あり資料番号: AA1730026077レポート番号: JAXA-SP-17-009E The 4th AKARI International Conference: The Cosmic Wheel and the Legacy of the AKARI archive: from galaxies and stars to planets and life (October 17-20, 2017. The University of Tokyo), Bunkyo-ku, Tokyo, JapanWe made systematic observations of the HI Br alpha (4.05 micrometers) and Br beta (2.63 micrometers) lines in 52 nearby (z less than 0.3) ULIRGs with AKARI. Our observations show that ULIRGs have a tendency to indicate higher Br beta/Br alpha line ratios than those observed in Galactic HII regions, and three galaxies in the observed sample show the anomaly of the Br beta/Br alpha line ratios (in the order of 1.0), which are significantly higher than that of case B (0.565). The high Br beta/Br alpha line ratios cannot be explained by the combination of the dust extinction and the case B, since dust extinction reduces the ratio. We simulate HII regions in the ULIRGs with the Cloudy code, and show that the high Br beta/Br alpha line ratios can be explained with the combination of the optically thick Br alpha line and the optically thin Br beta line. To achieve the column density large enough to make the Br alpha line optically thick, the gas density is required as high as n in the order of 10(exp 8) cm(exp -3). Hence our results suggest that star-formation activity in ULIRGs occurs preferentially in high-density clouds.Physical characteristics: Original contains color illustrations
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宇宙航空研究開発機構特別資料 = JAXA Special Publication: The Cosmic Wheel and the Legacy of the AKARI archive: from galaxies and stars to planets and life (17) 325-327 2018年3月9日第4回「あかり」国際会議 (2017年10月17-20日. 東京大学), 文京区, 東京形態: カラー図版あり資料番号: AA1730026063レポート番号: JAXA-SP-17-009E
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Astrophysical Journal 753(2) 2012年7月10日
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 63(2) 397-405 2011年4月
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SPACE TELESCOPES AND INSTRUMENTATION 2010: ULTRAVIOLET TO GAMMA RAY 7732 77320Z-77320Z-18 2010年
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 61 S327-S335 2009年1月
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 61 S377-S386 2009年1月
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 60 S317-S331 2008年2月
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PASJ : publications of the Astronomical Society of Japan 59(1) S257-S267 2007年1月31日Two ultraluminous X-ray sources (ULXs) in the nearby Sb galaxy NGC 1313, named X-1 and X-2, were observed with Suzaku on 2005 September 15. During the observation for a net exposure of 28 ks (but over a gross time span of 90 ks), both objects varied in intensity by about 50%. The 0.4–10 keV X-ray luminosities of X-1 and X-2 were measured as 2.5×1040 ergs-1 and 5.8×1039 ergs-1, respectively, with the former exhibiting the highest ever reported for this ULX. The spectrum of X-1 can be explained by the sum of a strong and variable powerlaw component with a high-energy cutoff, and a stable multicolor blackbody with an innermost disk temperature of ∼ 0.2keV. These results suggest that X-1 was in a "very high" state, where disk emission is strongly Comptonized. The absorber within NGC 1313 toward X-1 is suggested to have a subsolar oxygen abundance. The spectrum of X-2 is best represented, in its fainter phase, by a multicolor blackbody model with an innermost disk temperature of 1.2–1.3 keV, and becomes flatter as the source becomes brighter. Hence, X-2 is interpreted to be in a slim-disk state. These results suggest that the two ULXs have black hole masses of some dozens to a few hundred of solar masses.
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PUBLICATIONS OF THE ASTRONOMICAL SOCIETY OF JAPAN 59 S53-S76 2007年1月
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ASTROPHYSICAL JOURNAL 645(1) 256-263 2006年7月
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PROCEEDINGS OF THE X-RAY UNIVERSE 2005, VOLS 1 AND 2 604 569-+ 2006年
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Space Telescopes and Instrumentation II: Ultraviolet to Gamma Ray, Pts 1 and 2 6266(No.) U2663-U2663 2006年
講演・口頭発表等
24-
The 32nd Texas Symposium on Relativistic Astrophysics 2023年12月15日
共同研究・競争的資金等の研究課題
4-
日本学術振興会 科学研究費助成事業 2023年4月 - 2026年3月
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日本学術振興会 科学研究費助成事業 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 2010年 - 2012年
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日本学術振興会 科学研究費助成事業 2008年 - 2011年