09:30 〜 09:45
[PEM15-03] 相対論的衝撃波からのシンクロトロンメーザー放射
キーワード：衝撃波、プラズマ不安定性、高エネルギー天体現象
The origin of fast radio bursts (FRBs; Lorimer et al. 2007) is one of the unsolved problems in astrophysics. Since the high intensity and short duration of FRBs suggest extraordinarily high brightness temperature, the standard emission mechanisms such as synchrotron radiation and thermal bremsstrahlung cannot explain the origin of FRBs. Therefore, FRBs are believed to be coherent emission in the sense that electrons coherently move and radiate electromagnetic waves like emission from a single macro particle.
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). SMI has been widely studied in space physics and is well known as emission mechanism of auroral kilometric radiation and Jovian decametric radiation. Recently, the SMI is used for the model of FRBs (e.g., Lyubarsky 2014; Beloborodov 2017; Plotnikov & Sironi 2019; Metzger et al. 2019) and attracts much of attention in astrophysics. In this study, by performing particle-in-cell (PIC) simulation of relativistic shocks, we will demonstrate that large-amplitude electromagnetic waves are indeed excited by the SMI. Especially for relatively high magnetization, 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.
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). SMI has been widely studied in space physics and is well known as emission mechanism of auroral kilometric radiation and Jovian decametric radiation. Recently, the SMI is used for the model of FRBs (e.g., Lyubarsky 2014; Beloborodov 2017; Plotnikov & Sironi 2019; Metzger et al. 2019) and attracts much of attention in astrophysics. In this study, by performing particle-in-cell (PIC) simulation of relativistic shocks, we will demonstrate that large-amplitude electromagnetic waves are indeed excited by the SMI. Especially for relatively high magnetization, 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.