Bianchi-I cosmology from causal thermodynamics

TL;DR

This paper explores Bianchi-I cosmological models with viscous fluids using causal thermodynamics, presenting exact solutions including anisotropic de Sitter-like geometries and an isotropic accelerating universe without a cosmological constant.

Contribution

It introduces a novel approach to modeling anisotropic cosmologies with viscous fluids via second-order causal thermodynamics, providing new exact solutions and qualitative insights.

Findings

Exact anisotropic de Sitter and anti-de Sitter solutions

An asymptotically isotropic spacetime with constant acceleration

General behavior of solutions for linear barotropic fluids

Abstract

We investigate diagonal Bianchi-I spacetimes in the presence of viscous fluids by using the shear and the anisotropic pressure components as the basic variables, where the viscosity is driven by the (second-order) causal thermodynamics. A few exact solutions are presented, among which we mention the anisotropic versions of de Sitter/anti-de Sitter geometries as well as an asymptotically isotropic spacetime presenting an effective constant cosmic acceleration without any cosmological constant. The qualitative analysis of the solutions for barotropic fluids with linear equations of state suggests that the behaviour is quite general.