JpGU-AGU Joint Meeting 2020

Presentation information

[E] Poster

P (Space and Planetary Sciences ) » P-EM Solar-Terrestrial Sciences, Space Electromagnetism & Space Environment

[P-EM15] Plasma Theory and Simulation

convener:Seiji Zenitani(Kobe University), Fan Guo(Los Alamos National Laboratory), Takayuki Umeda(Institute for Space-Earth Environmental Research, Nagoya University), Takanobu Amano(Department of Earth and Planetary Science, University of Tokyo), Yasuhiro Nariyuki(Faculty of Education, University of Toyama)

[PEM15-P13] Synchrotron maser emission and associated particle acceleration in relativistic shocks

*Masanori Iwamoto1, Takanobu Amano2, Masahiro Hoshino2, Yosuke Matsumoto3 (1.Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 2.Graduate School of Science, The University of Tokyo, 3.Graduate School of Science, Chiba University)

Keywords:acceleration of particles, cosmic rays, shock waves

Relativistic shocks are ubiquitous in the universe, in which synchrotron maser instability produces intense electromagnetic precursor waves. Recent one-dimensional simulations show that longitudinal electrostatic waves, which are called wakefields, are induced in the wake of the large-amplitude electromagnetic waves and that nonthermal particles are generated during the nonlinear collapse of the wakefields (Lyubarsky 2006; Hoshino 2008). This particle acceleration may explain the origin of ultra-high-energy cosmic rays (Chen et al. 2002).
Although the synchrotron maser instability in the context of relativistic shocks are important for the cosmic ray acceleration, it has so far been discussed solely with one-dimensional simulations (e.g., Langdon et al. 1988) and it is not well known whether the same mechanism can operate in more realistic multidimensional systems. However, our high-resolution two-dimensional (2D) PIC simulations (Iwamoto et al. 2017, 2018) showed that the wave emission continues with substantial amplitude for the first time. We confirmed that the large-amplitude electromagnetic precursor waves continue to persist and that the wakefields are indeed excited by the intense electromagnetic waves (Iwamoto et al. 2019). The wakefields collapse during the nonlinear process of the parametric decay instability in the near-upstream region, where both ions and electrons are accelerated by the motional electric field in the upstream and produce clear nonthermal tails in the particle energy spectra measured in the upstream rest frame. In this talk, we discuss this particle acceleration and wave-plasma interaction for more details.