Bianchi Type V Universe with Bulk Viscous Matter and Time Varying Gravitational and Cosmological Constants

TL;DR

This paper explores Bianchi type V cosmological models with bulk viscous matter, where both gravitational and cosmological constants vary over time, and finds solutions compatible with astronomical observations.

Contribution

It introduces explicit solutions for Bianchi type V models with variable G and Λ, incorporating bulk viscosity proportional to Hubble parameter, and analyzes their physical properties.

Findings

Models are consistent with observational data.

Bulk viscosity affects the universe's expansion dynamics.

Variable G and Λ influence the anisotropic evolution.

Abstract

Spatially homogeneous and anisotropic Bianchi type V space-time with bulk viscous fluid source and time varying gravitational constant $G$ and cosmological term $\Lambda$ are considered. Coefficient of bulk viscosity $\zeta$ is assumed as a simple linear function of Hubble parameter $H$ (i.e. $\zeta=\zeta_0+\zeta_1 H$, where $\zeta_0$ and $\zeta_1$ are constants). The Einstein field equations are solved explicitly by using a law of variation for the Hubble parameter, which yields a constant value of deceleration parameter. Physical and kinematical parameters of the models are discussed. The models are found to be compatible with the results of astronomical observations.