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 教授東京大学 大学院理学系研究科 物理学専攻 教授
- 学位
- 博士(理学)(東京大学)修士(理学)(東京大学)
- J-GLOBAL ID
- 200901060914122911
- researchmap会員ID
- 1000363024
- 外部リンク
研究キーワード
5研究分野
1委員歴
3-
2014年4月 - 現在
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2011年9月 - 現在
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2006年 - 2009年
受賞
2論文
382-
Astronomy & Astrophysics 2023年10月
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The Astrophysical Journal 2023年8月1日
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The Astrophysical Journal 2023年7月1日
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The Astronomical Journal 165(4) 162-162 2023年3月17日Abstract The Subaru telescope is currently performing a strategic program (SSP) using the high-precision near-infrared (NIR) spectrometer IRD to search for exoplanets around nearby mid/late M dwarfs via radial velocity (RV) monitoring. As part of the observing strategy for the exoplanet survey, signatures of massive companions such as RV trends are used to reduce the priority of those stars. However, this RV information remains useful for studying the stellar multiplicity of nearby M dwarfs. To search for companions around such “deprioritized” M dwarfs, we observed 14 IRD-SSP targets using Keck/NIRC2 with pyramid wave-front sensing at NIR wavelengths, leading to high sensitivity to substellar-mass companions within a few arcseconds. We detected two new companions (LSPM J1002+1459 B and LSPM J2204+1505 B) and two new candidates that are likely companions (LSPM J0825+6902 B and LSPM J1645+0444 B), as well as one known companion. Including two known companions resolved by the IRD fiber injection module camera, we detected seven (four new) companions at projected separations between ∼2 and 20 au in total. A comparison of the colors with the spectral library suggests that LSPM J2204+1505 B and LSPM J0825+6902 B are located at the boundary between late M and early L spectral types. Our deep high-contrast imaging for targets where no bright companions were resolved did not reveal any additional companion candidates. The NIRC2 detection limits could constrain potential substellar-mass companions (∼10–75 MJup) at 10 au or further. The failure with Keck/NIRC2 around the IRD-SSP stars having significant RV trends makes these objects promising targets for further RV monitoring or deeper imaging with the James Webb Space Telescope to search for smaller-mass companions below the NIRC2 detection limits.
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The Astronomical Journal 2023年2月1日
MISC
674-
The Astrophysical Journal 928(2) 184-184 2022年2月22日The ultraluminous infrared galaxy IRAS 17208$-$0014 is a late-stage merger that hosts a buried active galactic nucleus (AGN). To investigate its nuclear structure, we performed high spatial resolution ($\sim0.\!\!^{\prime\prime}04\sim32\,\mathrm{pc}$) Atacama Large Millimeter/submillimeter Array (ALMA) observations in Band 9 ($\sim$450\,\micron\ or $\sim$660\,GHz), along with near-infrared AKARI spectroscopy in 2.5--5.0\,\micron. The Band 9 dust continuum peaks at the AGN location, and toward this position CO($J$=6--5) and CS($J$=14--13) are detected in absorption. Comparison with non-local thermal equilibrium calculations indicates that, within the central beam ($r\sim20\,\mathrm{pc}$), there exists a concentrated component that is dense ($10^7\,\mathrm{cm}^{-2}$) and warm ($>$200\,K) and has a large column density ($N_\mathrm{H_2}>10^{23}\,\mathrm{cm}^{-2}$). The AKARI spectrum shows deep and broad CO ro-vibrational absorption at 4.67\,\micron. Its band profile is well reproduced with a similarly dense and large column but hotter ($\sim$1000\,K) gas. The region observed through absorption in the near-infrared is highly likely in the nuclear direction, as in the sub-millimeter, but with a narrower beam including a region closer to the nucleus. The central component is considered to possess a hot structure where vibrationally excited HCN emission originates. The most plausible heating source for the gas is X-rays from the AGN. The AKARI spectrum does not show other AGN signs in 2.5--4\,\micron, but this absence may be usual for AGNs buried in a hot mid-infrared core. Besides, based on our ALMA observations, we relate various nuclear structures of IRAS 17208$-$0014 that have been proposed in the literature.
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Publications of the Astronomical Society of Australia 36 2019年Space Infrared Telescope for Cosmology and Astrophysics (SPICA), the cryogenic infrared space telescope recently pre-selected for a 'Phase A' concept study as one of the three remaining candidates for European Space Agency (ESA's) fifth medium class (M5) mission, is foreseen to include a far-infrared polarimetric imager [SPICA-POL, now called B-fields with BOlometers and Polarizers (B-BOP)], which would offer a unique opportunity to resolve major issues in our understanding of the nearby, cold magnetised Universe. This paper presents an overview of the main science drivers for B-BOP, including high dynamic range polarimetric imaging of the cold interstellar medium (ISM) in both our Milky Way and nearby galaxies. Thanks to a cooled telescope, B-BOP will deliver wide-field 100-350 µm images of linearly polarised dust emission in Stokes Q and U with a resolution, signal-to-noise ratio, and both intensity and spatial dynamic ranges comparable to those achieved by Herschel images of the cold ISM in total intensity (Stokes I). The B-BOP 200 µm images will also have a factor ∼30 higher resolution than Planck polarisation data. This will make B-BOP a unique tool for characterising the statistical properties of the magnetised ISM and probing the role of magnetic fields in the formation and evolution of the interstellar web of dusty molecular filaments giving birth to most stars in our Galaxy. B-BOP will also be a powerful instrument for studying the magnetism of nearby galaxies and testing Galactic dynamo models, constraining the physics of dust grain alignment, informing the problem of the interaction of cosmic rays with molecular clouds, tracing magnetic fields in the inner layers of protoplanetary disks, and monitoring accretion bursts in embedded protostars.
共同研究・競争的資金等の研究課題
49-
日本学術振興会 科学研究費助成事業 2023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 2023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 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 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 2023年6月 - 2025年3月
● 専任大学名
1-
専任大学名東京大学（University of Tokyo)
