The distribution of shock waves in driven supersonic turbulence

TL;DR

This paper analyzes shock wave distributions in three-dimensional simulations of driven supersonic turbulence, revealing a power-law distribution of shock strengths and effects of magnetic fields and self-gravity on shock characteristics.

Contribution

It provides the first detailed analysis of shock strength distributions in driven supersonic turbulence, including effects of magnetic fields and self-gravity.

Findings

Power law distribution of shock strengths with inverse square root relation.

High speed shock tail steeper than Gaussian due to superposition of waves.

Magnetic fields alter shock orientation distribution.

Abstract

Supersonic turbulence generates distributions of shock waves. Here, we analyse the shock waves in three-dimensional numerical simulations of uniformly driven supersonic turbulence, with and without magnetohydrodynamics and self-gravity. We can identify the nature of the turbulence by measuring the distribution of the shock strengths. We find that uniformly driven turbulence possesses a power law distribution of fast shocks with the number of shocks inversely proportional to the square root of the shock jump speed. A tail of high speed shocks steeper than Gaussian results from the random superposition of driving waves which decay rapidly. The energy is dissipated by a small range of fast shocks. These results contrast with the exponential distribution and slow shock dissipation associated with decaying turbulence. A strong magnetic field enhances the shock number transverse to the field direction at the expense of parallel shocks. A simulation with self-gravity demonstrates the development of a number of highly dissipative accretion shocks. Finally, we examine the dynamics to demonstrate how the power-law behaviour arises.