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 助教総合研究大学院大学 物理科学研究科 宇宙科学専攻 助教
- 学位
- 博士 (理学)(2005年3月 東京大学)
- 研究者番号
- 90403641
- ORCID ID
https://orcid.org/0000-0003-4384-9568- J-GLOBAL ID
- 201101033666007265
- researchmap会員ID
- B000004312
経歴
3-
2007年4月 - 現在
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2007年4月 - 現在
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2005年4月 - 2007年3月
論文
118-
Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 91-91 2024年8月23日
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Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 86-86 2024年8月23日
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Space Telescopes and Instrumentation 2024: Optical, Infrared, and Millimeter Wave 203-203 2024年8月23日
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Space Telescopes and Instrumentation 2024: Ultraviolet to Gamma Ray 75-75 2024年8月21日
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NUCLEAR INSTRUMENTS & METHODS IN PHYSICS RESEARCH SECTION A-ACCELERATORS SPECTROMETERS DETECTORS AND ASSOCIATED EQUIPMENT 1064 2024年7月 査読有り
MISC
87-
Proceedings of Science 2014年
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Proceedings of the International Astronomical Union 9(304) 106-107 2014年
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ASTROPHYSICAL JOURNAL LETTERS 781(1) 2014年1月
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2013年5月15日We conducted the first multi-frequency polarimetric imaging of four broad<br /> absorption line (BAL) quasars using Very Long Baseline Array at milli-arcsecond<br /> resolutions to investigate the inclination of the non-thermal jet and test the<br /> hypothesis that radio sources in BAL quasars are still young. Among these four<br /> sources, J0928+446, J1018+0530, and J1405+4056 show one-sided structures in<br /> parsec scales, and polarized emission detected in the core. These<br /> characteristics are consistent with those of blazars. We set constraints on<br /> viewing angles to $<$66 deg for these jets, in the framework of a Doppler<br /> beaming effect. J1159+0112 exhibits an unpolarized gigahertz peaked spectrum<br /> component and several discrete blobs with steep spectra on both sides of the<br /> central component across $\sim$1 kpc. These properties are consistent with<br /> those of young radio sources. We discuss the structures of jets and AGN wind.
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日本物理学会講演概要集 68(1) 138-138 2013年3月26日
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PASJ : publications of the Astronomical Society of Japan 64(5) "109-1"-"109-8" 2012年10月25日
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Proceedings of the International Astronomical Union 8(287) 288-289 2012年7月 査読有り
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2011年6月15日The nearby low-luminosity active galactic nucleus (LLAGN) NGC 4258 has a weak<br /> radio continuum emission at the galactic center. Quasi-simultaneous<br /> multi-frequency observations using the Very Large Array (VLA) from 5 GHz (6 cm)<br /> to 22 GHz (1.3 cm) showed inverted spectra in all epochs, which were<br /> intra-month variable, as well as complicated spectral features that cannot be<br /> represented by a simple power law, indicating multiple blobs in nuclear jets.<br /> Using the Nobeyama Millimeter Array (NMA), we discovered a large amplitude<br /> variable emission at 100 GHz (3 mm), which had higher flux densities at most<br /> epochs than those of the VLA observations. A James Clerk Maxwell Telescope<br /> (JCMT) observation at 347 GHz (850 micron) served an upper limit of dust<br /> contamination. The inverted radio spectrum of the nucleus NGC 4258 is<br /> suggestive of an analogy to our Galactic center Sgr A*, but with three orders<br /> of magnitude higher radio luminosity. In addition to the LLAGN M 81, we discuss<br /> the nucleus of NGC 4258 as another up-scaled version of Sgr A*.
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電子情報通信学会技術研究報告. A・P, アンテナ・伝播 109(1) 1-5 2009年4月2日我々は、電波天文衛星(ASTRO-G)搭載望遠鏡と、地上の電波望遠鏡との間でVLBI観測を行い、地球上だけでは不可能である超高分解能電波観測を行うことを計画している。ここでは衛星搭載電波望遠鏡光学系および搭載8GHz帯受信機の開発状況について報告する。この望遠鏡は口径約9メートルの主鏡で構成されるオフセットカセグレンアンテナであり、カセグレン焦点付近に、43,22,8GHz帯のフィードホーンを並置する。フィードホーンとしてマルチモードホーンを採用し、効率のよいカセグレン光学系を設計した。
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PASJ : publications of the Astronomical Society of Japan 60(1) 23-35 2008年2月25日
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Proceedings of the International Astronomical Union 3(242) 176-177 2007年3月 査読有り
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Proceedings of the International Astronomical Union 3(242) 148-149 2007年3月 査読有り筆頭著者
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Astrophys.J.648:148-157,2006 2006年5月12日We present a study of the kinematic and spectral ages of the Gigahertz-Peaked<br /> Spectrum (GPS) source CTD~93. Measurements of the hot spot separation over 8.5<br /> yr show evidence of an increase. The separation rate along the source axis is<br /> 0.34$\pm0.11c$ (H$_{0}$=72 km s$^{-1}$ Mpc$^{-1}$), which results in a<br /> kinematic age of 2200$\pm$700 yr. Assuming that two hot spots are moving apart<br /> at equal speeds, we derive an advance speed of 0.17$\pm0.06c$. The radio lobe<br /> spectra show a high frequency steepening, as expected if energetic electrons<br /> lose energy by synchrotron radiation. The spectral break decreases with the<br /> distance from the hot spot in the northern component of CTD~93. This tendency<br /> is expected from the basic scenario of radio lobe evolution involving particle<br /> acceleration at the hot spots, with the radio lobes populated by high energy<br /> electrons which have leaked from the hot spots. Although a core-jet morphology<br /> for CTD~93 has previously been proposed, these results indicate that the<br /> morphology is similar to that of Compact Symmetric Object (CSO). From the<br /> spectral fits in the northern component we found a break frequency of 3.7 GHz<br /> at the edge of the lobe. The resultant spectral age is $\sim$300 yr assuming<br /> the equipartition magnetic field. This requires the advance speed of 0.26$c$,<br /> which shows a good agreement of the hot spot motion of 0.17$\pm0.06c$. Our<br /> results strongly support the hypothesis that CSOs are young radio sources.
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Publications of the Astronomical Society of Japan 60 1069-1075We present the proper motions of H2O masers in NML Cygni, observed with the Japanese VLBI Network at three epochs spanning 455 d. We detected about 15 maser features at each epoch. Overall, 13 features that were detected at least twice were tracked by their radial velocities and proper motions. The three-dimensional kinematics of the maser features indicate the presence of an expanding outflow. The major axis of the outflow is estimated to be at a position angle of ∼ 108°, and an inclination angle of ∼ 8° with respect to the line of sight. The H2O masers are located between an apparent minimum radius of ∼ 9.6 × 1012 m (64 AU) and a maximum radius of ∼ 3.0 × 1013 m (202AU), where the expansion velocity increases from 12 to 27 km s-1. A comparison with the distributions of SiO, H2O, and OH masers suggests that the outflow of NML Cygni is expanding outside a radius of ∼ 1.5 × 10 13 m (100 AU). This radius corresponds to 6 stellar radii, and is consistent with the radius of the inner boundary for the dust shell. © 2008. Astronomical Society of Japan.
講演・口頭発表等
28共同研究・競争的資金等の研究課題
12-
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 基盤研究(C) 2020年4月 - 2023年3月
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日本学術振興会 科学研究費(基盤研究(B)) 2017年4月 - 2020年3月
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カシオ科学振興財団 研究助成金 2016年10月 - 2017年11月
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日本学術振興会 科学研究費助成事業 2014年4月 - 2017年3月
