Bianchi Type I Universes with Causal Bulk Viscous Cosmological Fluid

TL;DR

This paper investigates the evolution of Bianchi type I universes filled with a causal bulk viscous fluid, analyzing how viscosity affects cosmic dynamics and thermodynamics in anisotropic models.

Contribution

It introduces a detailed analysis of causal bulk viscous effects in Bianchi type I cosmologies with specific equations of state, including thermodynamic evolution.

Findings

Models satisfy small viscous stress condition

Derived evolution of relaxation time, temperature, and entropy

Shows impact of viscosity on anisotropic universe dynamics

Abstract

We consider the dynamics of a causal bulk viscous cosmological fluid filled constantly decelerating Bianchi type I space-time. The matter component of the Universe is assumed to satisfy a linear barotropic equation of state and the state equation of the small temperature Boltzmann gas. The resulting cosmological models satisfy the condition of smallness of the viscous stress. The time evolution of the relaxation time, temperature, bulk viscosity coefficient and comoving entropy of the dissipative fluid is also obtained.