Viscous FRW model with particle creation in the early universe

TL;DR

This paper explores how bulk viscosity and particle creation influence the early universe's evolution, providing exact solutions that describe transitions from inflation to radiation dominance, highlighting conditions for singular and non-singular origins.

Contribution

It introduces a comprehensive model combining bulk viscosity and particle creation effects with exact solutions in the early universe context.

Findings

Models can exhibit both singular and non-singular beginnings.

Analytical solutions for particle density and entropy are derived.

The evolution transitions from inflationary to radiation-dominated phases.

Abstract

We discuss the dynamical effects of bulk viscosity and particle creation on the early evolution of the Friedmann -Robertson -Walker model in the framework of open thermodynamical systems. We consider bulk viscosity and Particle creation as separate irreversible processes. Exact solutions of the Einstein field equations are obtained by using the "gamma-law" equation of state $p=(\gamma -1)\rho$, where the adiabatic parameter $\gamma$ varies with scale factor of the metric. We consider the cosmological model to study the early phases of the evolution of the universe as it goes from an inflationary phase to a radiation -dominated era in the presence of bulk viscosity and particle creation. Analytical solutions are obtained for particle number density and entropy for all models. It is seen that, by choosing appropriate functions for particle creation rate and bulk viscous coefficient, the models exhibit singular and non-singular beginnings.