Magnetic relaxation in the Bianchi-I universe

TL;DR

This paper investigates the evolution of a magnetized Bianchi-I universe using an extended Einstein-Maxwell model, revealing non-monotonic anisotropic expansion and a phenomenon where magnetization screens the magnetic field.

Contribution

It introduces an extended constitutive equation for medium magnetization and provides exact solutions showing novel anisotropic expansion behaviors.

Findings

Non-monotonic anisotropic expansion in Bianchi-I universe

Existence of evolution with hidden magnetic field where magnetic effects are screened

Exact solutions to extended Einstein-Maxwell equations

Abstract

Extended Einstein-Maxwell model and its application to the problem of evolution of magnetized Bianchi-I Universe are considered. The evolution of medium magnetization is governed by a relaxation type extended constitutive equation. The series of exact solutions to the extended master equations is obtained and discussed. The anisotropic expansion of the Bianchi-I Universe is shown to become non-monotonic (accelerated/decelerated) in both principal directions (along the magnetic field and orthogonal to it). A specific type of expansion, the so-called evolution with hidden magnetic field, is shown to appear when the magnetization effectively screens the magnetic field and the latter disappears from the equations for gravitational field.