Magnetohydrodynamics and Plasma Cosmology

TL;DR

This paper investigates the behavior of magnetized fluids in cosmology, analyzing linear MHD equations in both Newtonian and relativistic frameworks, and explores how magnetic fields influence cosmological perturbations and instabilities.

Contribution

It provides a comprehensive analysis of linear MHD equations in cosmological contexts, including instability criteria and the excitation of various perturbation modes in anisotropic spacetimes.

Findings

Identification of instability criteria for viscous magnetized fluids.

Demonstration of excitation of acoustic, electromagnetic, and fast-magnetosonic modes.

Implications for the role of magnetic fields in cosmological evolution.

Abstract

We study the linear magnetohydrodynamic (MHD) equations, both in the Newtonian and the general-relativistic limit, as regards a viscous magnetized fluid of finite conductivity and discuss instability criteria. In addition, we explore the excitation of cosmological perturbations in anisotropic spacetimes, in the presence of an ambient magnetic field. Acoustic, electromagnetic (e/m) and fast-magnetosonic modes, propagating normal to the magnetic field, can be excited, resulting in several implications of cosmological significance.