On the locally rotationally symmetric Einstein-Maxwell perfect fluid

TL;DR

This paper analyzes the stability of Einstein-Maxwell perfect fluid configurations with symmetry using a hyperbolic formalism, providing a classification of stable and unstable states influenced by sound speed and conductivity.

Contribution

It introduces a $1+1+2$-tetrad formalism for stability analysis and offers a comprehensive classification of stability conditions for symmetric Einstein-Maxwell fluids.

Findings

Stability conditions depend on sound speed and electrical conductivity.

A threshold for instability emerges in both contracting and expanding systems.

Nonlinear stability for infinitely conducting plasma is also discussed.

Abstract

We examine the stability of an Einstein-Maxwell perfect fluid configuration with a privileged direction of symmetry by means of a $1+1+2$-tetrad formalism. We use this formalism to cast, in a quasi linear symmetric hyperbolic form the equations describing the evolution of the system. This hyperbolic reduction is used to discuss the stability of solutions of the linear perturbation. By restricting the analysis to isotropic fluid configurations, we made use of a constant electrical conductivity coefficient for the fluid (plasma), and the nonlinear stability for the case of an infinitely conducting plasma is also considered. As a result of this analysis we provide a complete classification and characterization of various stable and unstable configurations. We found in particular that in many cases the stability conditions is strongly determined by the constitutive equations by means of the square of the velocity of sound and the electric conductivity, and a threshold for the emergence of the instability appears in both contracting and expanding systems.