Inflationary scenario in Bianchi Type V space-time for a barotropic fluid distribution with variable bulk viscosity and vacuum energy density

Abstract

We examine an inflationary scenario in Bianchi Type V space-time for a barotropic fluid distribution with variable bulk viscosity and decaying vacuum energy density. We observe that the matter density ρ, the coefficient of bulk viscosity ζ and the expansion θ all diverge at τ = 0. The spatial volume increases with time, representing an inflationary scenario. The deceleration parameter q < 0 for barotropic, dust and radiation dominated models representing an accelerated universe, while for a stiff fluid distribution q > 0 corresponding to a decelerated universe. The vacuum energy density Λ decreases with time. The entropy per unit volume is proportional to the absolute temperature. The energy conditions (weak, dominant and strong) are discussed for the model. The reality condition ρ + p ≥ 0 is violated for the inflationary model due to the presence of a scalar field (φ). We also discuss the importance of Bianchi Type V model where the anisotropy dies away during the inflationary era. We also calculate the inflationary parameters and compare the results with the Planck data and discuss their compatibility with anisotropy and BAO estimates. The cosmological constant Λ is a function of time without break general covariance. We also discuss the bounds of the model, how the model isotropizes, where the fluid goes after inflation and how viscosity may realize a graceful exit from inflation to a radiation dominated era.