Precursor Wave Amplification by Ion-Electron Coupling through Wakefield in Relativistic Shocks

TL;DR

This paper demonstrates that ion-electron coupling via wakefields significantly amplifies precursor electromagnetic waves in relativistic shocks, with implications for high-energy astrophysical phenomena.

Contribution

It reveals a positive feedback mechanism involving wakefields that enhances wave amplitude and leads to particle acceleration in relativistic shocks.

Findings

Wave amplitude is significantly amplified by ion-electron wakefield coupling.

Wakefields collapse during parametric decay instability, generating nonthermal particles.

Intense coherent emission and particle acceleration occur in high-energy astrophysical environments.

Abstract

We investigated electromagnetic precursor wave emission in relativistic shocks by using two-dimensional particle-in-cell simulations. We found that the wave amplitude is significantly enhanced by a positive feedback process associated with ion-electron coupling through the wakefields for high magnetization. The wakefields collapse during the nonlinear process of the parametric decay instability in the near-upstream region, where nonthermal electrons and ions are generated. The intense coherent emission and the particle acceleration may opperate in high-energy astrophysical objects.