Bulk Viscous Solutions to the Field Equations and the Deceleration Parameter-Revisited

TL;DR

This paper explores solutions to Einstein's field equations incorporating bulk viscosity, variable constants, and a constant deceleration parameter, aligning with supernovae observations and expanding cosmological models.

Contribution

It introduces a new class of solutions in Robertson-Walker spacetimes with bulk viscosity and variable constants, emphasizing a constant deceleration parameter.

Findings

Deceleration parameter can be negative, consistent with supernovae Ia data.

Bulk viscosity modeled as a power function of density.

New solutions extend cosmological models with variable constants.

Abstract

We utilise a form for the Hubble parameter to generate a number of solutions to the Einstein field equations with variable cosmological constant and variable gravitational constant in the presence of a bulk viscous fluid. The Hubble law utilised yields a constant value for the deceleration parameter. A new class of solutions is presented in the Robertson-Walker spacetimes. The coefficient of bulk viscosity is assumed to be a power function of the mass density. For a class of solutions, the deceleration parameter is negative which is consistent with the supernovae Ia observations.