Study for cosmic-ray acceleration in partially ionized plasmas and application to the early universe
Project/Area Number |
16K17702
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Research Category |
Grant-in-Aid for Young Scientists (B)
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Allocation Type | Multi-year Fund |
Research Field |
Particle/Nuclear/Cosmic ray/Astro physics
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Research Institution | The University of Tokyo (2017-2019) Aoyama Gakuin University (2016) |
Principal Investigator |
Ohira Yutaka 東京大学, 大学院理学系研究科(理学部), 助教 (40589347)
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Project Period (FY) |
2016-04-01 – 2020-03-31
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Project Status |
Completed (Fiscal Year 2019)
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Budget Amount *help |
¥3,900,000 (Direct Cost: ¥3,000,000、Indirect Cost: ¥900,000)
Fiscal Year 2018: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2017: ¥1,170,000 (Direct Cost: ¥900,000、Indirect Cost: ¥270,000)
Fiscal Year 2016: ¥1,560,000 (Direct Cost: ¥1,200,000、Indirect Cost: ¥360,000)
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Keywords | 宇宙線 / 超新星残骸 / プラズマ / 磁場 / 衝撃波 / 初期宇宙 / 宇宙物理 / 理論天文学 / プラズマ・核融合 |
Outline of Final Research Achievements |
We first performed plasma particle simulations for collisionless shocks propagating to partially ionized plasmas. We showed that some of downstream hot hydrogens that are generated by the charge exchange process leak into the shock upstream region. After the leaking neutral atoms are ionized, the ionized particles change the shock structure. In addition, we first showed that there is the critical ionization fraction that controls the cosmic-ray acceleration. Furthermore, we investigated the cosmic-ray acceleration in the early universe. We showed that the first cosmic rays are accelerated by first supernova remnants at z ~ 20. The maximum energy of the first cosmic ray is about 1 GeV. Moreover, we showed that accretion shocks associated with cosmological large scale structure formation at z ~ 20 cannot accelerate cosmic rays because of a low ionization fraction.
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Academic Significance and Societal Importance of the Research Achievements |
エネルギーの高い宇宙線は、宇宙の様々な天体に影響を及ぼす。地球でも、半導体エラーや雲や雷に影響を及ぼす。このように地球上から宇宙に渡って至る所に影響を及ぼす宇宙線は、いまだその加速源がわかっていない。本研究は、これまで完全電離を仮定して議論されていた宇宙線加速過程を見直し、より現実的な部分電離プラズマ中での宇宙線加速過程を調べた。その結果、これまでいつでも宇宙線を加速できると思われていた無衝突衝撃波は、電離度によっては宇宙線加速に適さないことが明らかになった。これは、未解明の宇宙線源の候補を絞る上で非常に役に立つ結果である。
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Report
(5 results)
Research Products
(48 results)
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[Journal Article] Anomalous plasma acceleration in colliding high-power laser-produced plasmas2019
Author(s)
T. Morita, K. Nagashima, M. Edamoto, K. Tomita, T. Sano, Y. Itadani, R. Kumar, M. Ota, S. Egashira, R. Yamazaki, S. J. Tanaka, S. Tomita, S. Tomiya, H. Toda, I. Miyata, S. Kakuchi, S. Sei, N. Ishizaka, S. Matsukiyo, Y. Kuramitsu, Y. Ohira, M. Hoshino, and Y. Sakawa
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Journal Title
Physics of Plasmas
Volume: 26
Issue: 9
Pages: 090702-090702
DOI
Related Report
Peer Reviewed / Open Access / Int'l Joint Research
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[Journal Article] Multi-year X-ray variations of Iron-K and Continuum Emissions in the Young Supernoca Remnant Cassioeia A2017
Author(s)
Toshiki Sato, Yoshitomo Maeda, Aya Bamba, Satoru Katsuda, Yutaka Ohira, Ryo Yamazaki, Kuniaki Masai, Hironori Matsumoto, Makoto Sawada, Yukikatsu Terada, John P. Hughes & Manabu Ishida
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Journal Title
The Astrophysical Journal
Volume: 836
Issue: 2
Pages: 225-235
DOI
Related Report
Peer Reviewed / Int'l Joint Research / Acknowledgement Compliant
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[Journal Article] Suzaku observations of the hard X-ray spectrum of Vela Jr. (SNR RX J0852.0-4622)2016
Author(s)
Takeda, S., Bamba, A., Terada, Y., Tashiro, M. S., Katsuda, S., Yamazaki, R.,Ohira, Y., Iwakiri, W.
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Journal Title
Publications of the Astronomical Society of Japan
Volume: 68
Issue: SP1
DOI
Related Report
Peer Reviewed / Open Access / Int'l Joint Research / Acknowledgement Compliant
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