Effects of Bulk Viscosity on Cosmological Evolution

TL;DR

This paper investigates how bulk viscosity influences the evolution of homogeneous, isotropic cosmological models, deriving solutions that include power-law and exponential expansions, with implications for inflationary scenarios.

Contribution

It introduces new solutions for cosmological models with bulk viscosity, including power-law, exponential, and double exponential expansions, expanding understanding of viscous effects in cosmology.

Findings

Power-law expansion solutions related to extended inflation

Exponential solutions connected to old inflation

A novel exponential of exponential expansion solution

Abstract

The effect of bulk viscisity on the evolution of the homogeneous and isotropic cosmological models is considered. Solutions are found, with a barotropic equation of state, and a viscosity coefficient that is proportional to a power of the energy density of the universe. For flat space, power law expansions, related to extended inflation are found as well as exponential solutions, related to old inflation; also a solution with expansion that is an exponential of an exponential of the time is found.