The Generation and Dissipation of Interstellar Turbulence - Results from Large Scale High Resolution Simulations

TL;DR

This study uses high-resolution adaptive mesh simulations to analyze interstellar turbulence, revealing the injection scale around 75 pc, the nature of dissipative structures, and the effects of realistic physical conditions and stellar feedback.

Contribution

It presents the first high-resolution simulations of interstellar turbulence that include temperature variations and self-regulated stellar feedback, differing from previous isothermal and artificially forced models.

Findings

Injection scale of turbulence ~75 pc matches observations.

Dissipative structures follow log-Poisson statistics with shock dissipation.

Turbulence driven by stellar explosions without artificial forcing.

Abstract

We study, by means of adaptive mesh refinement hydro- and magnetohydrodynamical simulations that cover a wide range of scales (from kpc to sub-parsec), the dimension of the most dissipative structures and the injection scale of the turbulent interstellar gas, which we find to be about 75 pc, in agreement with observations. This is however smaller than the average size of superbubbles, but consistent with significant density and pressure changes in the ISM, which leads to the break-up of bubbles locally and hence to injection of turbulence. The scalings of the structure functions are consistent with log-Poisson statistics of supersonic turbulence where energy is dissipated mainly through shocks. Our simulations are different from previous ones by other authors as (i) we do not assume an isothermal gas, but have temperature variations of several orders of magnitude and (ii) we have no artificial forcing of the fluid with some ad hoc Fourier spectrum, but drive turbulence by stellar explosions at the Galactic rate, self-regulated by density and temperature thresholds imposed on the ISM gas.