The precursor structure in relativistic shocks

TL;DR

This paper develops a unified macroscopic framework for precursors in relativistic shocks, revealing how they transfer energy and momentum, influence shock stability, and can lead to turbulence at critical energy flux levels.

Contribution

It introduces a novel unifying framework for relativistic shock precursors and analyzes their impact on shock stability and turbulence onset.

Findings

Precursor energy transfer modifies shock structure.

Critical energy flux leads to shock disappearance.

Flow becomes turbulent at the sonic point.

Abstract

We present a common unifying macroscopic framework for precursors in relativistic shock waves. These precursors transfer energy and momentum from the hot downstream to the cold upstream, modifying the shock structure. Derishev & Piran (2016} have shown that in a steady state, there is a maximal fraction of the downstream energy flux that the precursor can carry. We show that at this critical value, the shock disappears, and the flow passes through a sonic point. This behavior resembles the classical Newtonian Rayleigh flow problem. At the critical value, the transition is unstable as perturbations in the upstream accumulate at the sonic point. Thus, if such a point is reached, the shock structure is drastically modified, and the flow becomes turbulent.