Establishing Theory of Electron Acceleration at Shocks Based on In-situ Observation

2021 Fiscal Year Final Research Report

• Project/Area Number: 17H02966
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Space and upper atmospheric physics
• Research Institution: The University of Tokyo
• Principal Investigator: Amano Takanobu 東京大学, 大学院理学系研究科(理学部), 准教授 (00514853)
• Co-Investigator(Kenkyū-buntansha): 松清 修一 九州大学, 総合理工学研究院, 准教授 (00380709)
• Project Period (FY): 2017-04-01 – 2021-03-31
• Keywords: プラズマ / 粒子加速 / 衝撃波 / プラズマ波動 / 宇宙線

Outline of Final Research Achievements

The efficiency of electron acceleration at shocks in space was investigated by combining theory, observational data analysis, as well as numerical simulations. A new theoretical model for acceleration of sub-relativistic electrons was proposed, which explains spacecraft observations of Earth’s bow shock. First-principles numerical simulations have also been conducted to investigate the effect of non-stationarity and survey the parameter dependence for application to shocks in various space environments. Judging from the obtained results, the model proposed in this research may be considered as the most promising candidate to resolve the long-standing issue of electron injection in the shock acceleration theory.

Free Research Field

宇宙空間物理学

Academic Significance and Societal Importance of the Research Achievements

高エネルギー粒子の加速は宇宙において普遍的に見られる現象であり，一部の粒子のみが熱的エネルギーよりも遥かに高いエネルギーまで加速されることが知られている．熱平衡状態から大きく逸脱した粒子を生成する機構として，最も有力視されているのが衝撃波における粒子加速機構である．本研究によって衝撃波粒子加速における最大の困難であった電子注入問題の解決に向けて大きな一歩を踏み出すことができた