[P-EM16] 宇宙プラズマ理論・シミュレーション

[PEM16-01] 3D PIC simulations of coherent emission from relativistic shocks

*岩本 昌倫¹、天野 孝伸²、松本 洋介³、松清 修一¹、星野 真弘² (1.九州大学総合理工学研究院、2.東京大学地球惑星科学専攻、3.千葉大学理学研究院)

キーワード：プラズマ不安定、衝撃波

The origin of fast radio bursts (FRBs; Lorimer et al. 2007) is one of the unsolved problems in astrophysics. Many observations of FRBs indicate that FRBs must be coherent emission in the sense that electrons coherently move and radiate electromagnetic waves. In relativistic shocks, it is well known that coherent electromagnetic waves are excited by synchrotron maser instability (SMI) in the shock transition (Hoshino & Arons 1991). The SMI, which is called cyclotron maser instability in the weakly relativistic context, is also known as the emission mechanism of coherent radio sources such as auroral kilometric radiation at Earth and Jovian decametric radiation. Recently, some models of fast radio burst based on the coherent emission from relativistic shock via the SMI have been proposed (e.g., Lyubarsky 2014; Beloborodov 2017; Plotnikov & Sironi 2019; Metzger et al. 2019) and the SMI in the context of relativistic shocks attracts more attention from astrophysics. In this study, by performing the world’s first three-dimensional (3D) particle-in-cell (PIC) simulation of relativistic shocks, we will demonstrate that large amplitude electromagnetic waves are indeed excited by the SMI even in 3D and that the wave amplitude is significantly amplified and exceeds that in pair plasmas due to a positive feedback process associated with ion electron coupling. Based on the simulation results, we will discuss the applicability of the SMI for FRBs in this talk.