Radiative and dynamic stability of a dilute plasma

TL;DR

This paper investigates the linear stability of dilute, hot plasmas with stratification and anisotropic conduction, revealing new overstabilities driven by radiative cooling and heat flux, relevant to galaxy cluster dynamics.

Contribution

It identifies previously unrecognized g-mode overstabilities in dilute plasmas caused by radiative cooling and heat flux effects, expanding understanding of plasma stability.

Findings

Discovery of g-mode overstabilities in dilute plasmas.

Implications for cold front formation in galaxy clusters.

Analysis of magnetic field configurations affecting stability.

Abstract

We analyze the linear stability of a dilute, hot plasma, taking into account the effects of stratification and anisotropic thermal conduction. The work is motivated by attempts to understand the dynamics of the intracluster medium in galaxy clusters. We show that magnetic field configurations that nominally stabilize either the heat-flux driven buoyancy instability (associated with a positive thermal gradient) or the magnetothermal instability (negative thermal gradient) can lead to previously unrecognized g-mode overstabilities. The driving source of the overstability is either radiative cooling (positive temperature gradient) or the heat flux itself (negative temperature gradient). While the implications of these overstabilities have yet to be explored, we speculate that the cold fronts observed in many relaxed galaxy clusters may be related to their non-linear evolution.