Bianchi II, VIII, and IX viscous fluid cosmology

TL;DR

This paper derives exact solutions for viscous fluid cosmologies in Bianchi II, VIII, and IX models, introducing new solutions for the latter two classes under specific assumptions.

Contribution

It presents new exact solutions for Bianchi VIII and IX viscous fluid models, expanding the understanding of anisotropic cosmologies with viscosity.

Findings

New solutions for Bianchi VIII and IX models.

Relations between matter density, expansion, and pressure.

Enhanced models of anisotropic viscous cosmologies.

Abstract

In this paper we study the exact solutions for a viscous fluid distribution in Bianchi II, VIII, and IX models. The metric is simplified by assuming a relationship between the coefficients and the metric tensor. Solutions are obtained in two special cases: in one, an additional assumption is made where the matter density and the expansion scalar have a definite relation and in the other a barotropic equation of state between the matter density and the thermodynamic pressure is assumed. While the Bianchi II solutions are already found in the literature the other two classes of solutions are apparently new.