Thermal instability with the effect of cosmic-ray diffusion

TL;DR

This paper investigates how cosmic rays influence thermal instability in plasmas, showing that CRs can slow down structure formation by reducing the growth rate of the instability, with effects depending on diffusion and pressure ratios.

Contribution

It introduces a model treating cosmic rays and thermal plasma as interacting fluids, highlighting the stabilizing effect of CRs on thermal instability.

Findings

CRs decrease the growth rate of thermal instability

The stabilizing effect depends on diffusion coefficient

Slower structure formation predicted with CRs

Abstract

We study dynamical effects of cosmics rays (CRs) on the thermal instability in the linear regime. CRs and the thermal plasma are treated as two different interacting fluids, in which CRs can diffuse along the magnetic field lines. We show that growth rate of the magnetothermal condensation mode is reduced because of the existence of CRs and this stabilizing effect depends on the diffusion coefficient and the ratio of the CRs pressure to gas pressure. Thus, a slower rate of structure formation via thermal instability is predicted when CRs are considered.