Collisionless tearing instability in relativistic non-thermal pair plasma and its application to MHD turbulence

TL;DR

This paper investigates the collisionless tearing instability in relativistic pair plasmas with non-thermal distributions, revealing how plasma conditions influence instability growth and applying findings to relativistic MHD turbulence relevant to astrophysical particle acceleration.

Contribution

It provides new insights into how particle spectra and plasma magnetization affect tearing instability in relativistic plasmas, with applications to astrophysical turbulence modeling.

Findings

Tearing mode suppressed as particle spectrum hardens when plasma pressure supports the current sheet.

In the force-free limit, the growth rate becomes independent of the particle spectrum.

Derived an expression for the size of turbulent eddies susceptible to tearing instability and identified a critical magnetization parameter.

Abstract

Collisionless tearing instability with a power-law distribution function in a relativistic pair plasma with a guide field is studied. When the current sheet is supported by plasma pressure, the tearing mode is suppressed as the particle spectrum hardens. In the force-free limit, the instability growth rate becomes independent of the particle spectrum. We apply these results to relativistic MHD turbulence, where magnetic energy greatly exceeds plasma rest energy, and derive an expression for the transverse size of turbulent eddies unstable to tearing mode. We also establish the critical plasma magnetization parameter above which charge starvation prevents the tearing instability. These results might be useful for developing more accurate models of particle acceleration in relativistic astrophysical sources.