Non Kolmogorov-like Turbulence in the Local Interstellar Medium

TL;DR

This paper presents a self-consistent model of turbulence in the local interstellar medium, showing that charge exchange processes lead to a steeper turbulent cascade than Kolmogorov's theory predicts.

Contribution

It introduces a novel model accounting for charge exchange effects in partially ionized magnetofluids, altering the understanding of turbulence in the ISM.

Findings

Turbulent correlation scales are larger than shock length-scales.

Charge exchange modifies spectral transfer in large-scale eddies.

Turbulent cascade is steeper than Kolmogorov's prediction.

Abstract

We develop a self-consistent model of turbulence in a local interstellar medium (ISM). The model describes a partially ionized magnetofluid ISM in which a neutral hydrogen fluid interacts with a plasma dominantly through a charge exchange. The ISM turbulent correlation scales in our model are much bigger than the shock characteristic length-scales. Unlike small length-scale linear collisional dissipation in the fluid, the charge exchange processes can be effective unpredictably on a variety of ISM length-scales depending upon the neutral and plasma densities, the charge exchange cross section and the characteristic length scales. We find, from scaling arguments that the charge exchange interactions modify spectral transfer associated with large-scale energy containing eddies. Consequently, the ISM turbulent cascade are steeper than those predicted by Kolmogorov's phenomenology.