惑星分光観測衛星プロジェクトチーム
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
-
2007年4月 - 現在
-
2005年4月 - 2007年3月
論文
97-
Monthly Notices of the Royal Astronomical Society 530(3) 2590-2607 2024年4月15日ABSTRACT A substantial fraction of quasars display broad absorption lines (BALs) in their rest-frame ultraviolet spectra. While the origin of BALs is thought to be related to the accretion disc wind, it remains unclear whether the observed ratio of BAL to non-BAL quasars is a result of orientation. We conducted observations of 48 BAL quasars and the same number of non-BAL quasars at 322 MHz using the Giant Metrewave Radio Telescope. Combined with previous flux measurements ranging from MHz to GHz frequencies, we compared continuum radio spectra between the two quasar groups. These data offer insights into low-frequency radio properties that have been difficult to investigate with previous observations only at GHz frequencies. Our results show that 73 ± 13 per cent of the BAL quasars exhibit steep or peaked spectra, a higher proportion than the 44 ± 14 per cent observed in the non-BAL quasars. In contrast, there are no discernible differences between the two quasar groups in the radio luminosity, peak frequency, and spectral index distributions of sources with steep or peaked spectra and sources with flat or inverted spectra. Generally, as the jet axis and line of sight become closer to parallel, quasars exhibit flat or inverted spectra rather than steep or peaked spectra. Therefore, these results suggest that BAL quasars are more frequently observed farther from the jet axis than non-BAL quasars. However, given that a certain proportion of BAL quasars exhibit flat or inverted spectra, more than the simple orientation scenario is required to elucidate the radio properties of BAL quasars.
-
Publications of the Astronomical Society of Japan 2023年10月3日 査読有り
-
The Astrophysical Journal 2023年7月1日 査読有り
-
Nature 616(7958) 686-690 2023年4月26日 査読有りAbstract The nearby radio galaxy M87 is a prime target for studying black hole accretion and jet formation1,2. Event Horizon Telescope observations of M87 in 2017, at a wavelength of 1.3 mm, revealed a ring-like structure, which was interpreted as gravitationally lensed emission around a central black hole3. Here we report images of M87 obtained in 2018, at a wavelength of 3.5 mm, showing that the compact radio core is spatially resolved. High-resolution imaging shows a ring-like structure of $${8.4}_{-1.1}^{+0.5}$$ Schwarzschild radii in diameter, approximately 50% larger than that seen at 1.3 mm. The outer edge at 3.5 mm is also larger than that at 1.3 mm. This larger and thicker ring indicates a substantial contribution from the accretion flow with absorption effects, in addition to the gravitationally lensed ring-like emission. The images show that the edge-brightened jet connects to the accretion flow of the black hole. Close to the black hole, the emission profile of the jet-launching region is wider than the expected profile of a black-hole-driven jet, suggesting the possible presence of a wind associated with the accretion flow.
MISC
64-
Space Telescopes and Instrumentation 2022: Ultraviolet to Gamma Ray 2022年8月31日
-
VLBI Future Planning Working Group Review Report, June 2021, 4th Edition 2021年6月
-
Space Telescopes and Instrumentation 2020: Optical, Infrared, and Millimeter Wave 2020年12月13日
-
Space Telescopes and Instrumentation 2020: Ultraviolet to Gamma Ray 2020年12月13日
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
-
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
-
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
-
カシオ科学振興財団 研究助成金 2016年10月 - 2017年11月
-
日本学術振興会 科学研究費助成事業 2014年4月 - 2017年3月
