日本地球惑星科学連合2023年大会

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[J] 口頭発表

セッション記号 P (宇宙惑星科学) » P-EM 太陽地球系科学・宇宙電磁気学・宇宙環境

[P-EM17] 宇宙プラズマ理論・シミュレーション

2023年5月22日(月) 13:45 〜 15:00 101 (幕張メッセ国際会議場)

コンビーナ:天野 孝伸(東京大学 地球惑星科学専攻)、三宅 洋平(神戸大学大学院システム情報学研究科)、梅田 隆行(名古屋大学 宇宙地球環境研究所)、中村 匡(福井県立大学)、座長:諌山 翔伍(九州大学総合理工学研究院)、天野 孝伸(東京大学 地球惑星科学専攻)

14:30 〜 14:45

[PEM17-09] Turbulences and heating in weakly magnetized, perpendicular shocks in the transrelativstic regime.

*Theo Abounnasr1 (1.Institute for Cosmic Ray Research, The University of Tokyo)


キーワード:Space Plasma, Instabilities, Gamma-ray bursts

Gamma-ray bursts (GRB) events are associated with relativistic shocks. The prompt emission is usually associated with internal, possibly mildly relativistic, shocks. There, a considerable amount of energy mostly carried by ions, can be converted into radiating high-energy electrons. While the detailed acceleration mechanism of the radiating population is debated, how the shock-energy is dissipated otherwise remains unclear. In the case of the ultra-relativistic shock-front decelerating in the interstellar medium, also associated the with the long-lasting "Afterglow" emission, detailed analysis of the spectrum and dedicated simulations bring out the possibility that significant energy is converted by heating the electrons in turbulence ahead of the shock.
It is unknown how varying Lorentz factor may affect the pre-heating and particle acceleration of a quasi-perpendicular shock. In this context, many unstable modes can grow at the same time, and it is not obvious which one will govern the dynamics of the plasma.
To clarify the situation, an overview of shock-driven kinetic instabilities is presented. Analytical estimates of the growth rates and typical coherence length over the transrelativistic regime are derived to determine the early linear evolution of the system. Relativistic beaming of a reflected population of ions is shown to affect the growth of electromagnetic modes. Heating of the plasma is shown to occur first in self-regulating electrostatic oblique modes, while turbulent electric fields propagating along the beam axis offer a persistent source of parallel heating, beneficial for the development of electromagnetic modes. The implications of saturation beyond the linear regime are discussed.