Relativistically Magnetized Collisionless Shocks in Pair Plasma: I. Solitons, Chaos, and Thermalization

TL;DR

This paper introduces a new theoretical model for relativistically magnetized collisionless shocks, highlighting the role of nonlinear particle dynamics and chaos in energy dissipation and shock structure formation.

Contribution

It presents a novel framework modeling shock dissipation via chaos in particle orbits, contrasting with traditional plasma collective interactions.

Findings

Shock dissipation driven by nonlinear particle chaos.

Magnetic field compression and downstream velocities match Rankine-Hugoniot conditions.

Entropy generation rate linked to Lyapunov spectrum.

Abstract

In this paper, the first in a series, we present a new theoretical model for the global structure and dissipation of relativistically magnetized collisionless shock waves. Quite remarkably, we find that in contrast to unmagnetized shocks, the leading energy dissipation channel does not involve collective plasma interactions. Rather, it is a consequence of nonlinear particle dynamics. We demonstrate that the kinetic-scale shock transition can be modeled as a stationary system consisting of a large set of cold beams coupled through the magnetic field. The fundamental mechanism governing shock dissipation relies on the onset of chaos in orbital dynamics within quasiperiodic solitonic structures. We discuss the impact of upstream temperature and magnetization on the shock profile, recovering the magnetic field compression, downstream velocities, and heating expected from the Rankine-Hugoniot jump conditions. We deduce a rate of entropy generation from the spectrum of Lyapunov exponents and discuss the thermalization of the beam distribution. Our model provides a general framework to study magnetized collisionless shock structures.