Dissipative cosmological solutions

TL;DR

This paper derives exact solutions to Einstein's equations for a homogeneous universe with viscous fluid sources, analyzing stability and comparing full and truncated theories, revealing new asymptotic behaviors.

Contribution

It provides the first exact solutions for a viscous fluid in cosmology at a specific viscosity index and examines their stability and asymptotic properties.

Findings

Friedmann solution is stable for m ≥ 1/2.

De Sitter solution is stable for m ≤ 1/2.

Solutions with extrema are replaced by asymptotically Minkowski evolutions at m=1/2.

Abstract

The exact general solution to the Einstein equations in a homogeneous Universe with a full causal viscous fluid source for the bulk viscosity index $m=1/2$ is found. We have investigated the asymptotic stability of Friedmann and de Sitter solutions, the former is stable for $m\ge 1/2$ and the latter for $m\le 1/2$. The comparison with results of the truncated theory is made. For $m=1/2$, it was found that families of solutions with extrema no longer remain in the full case, and they are replaced by asymptotically Minkowski evolutions. These solutions are monotonic.