Cosmological constant dominated transit universe from early deceleration to current acceleration phase in Bianchi-V space-time

TL;DR

This paper models the universe's transition from deceleration to acceleration using viscous fluid and a time-dependent cosmological constant in Bianchi-V space-time, aligning with recent supernovae observations.

Contribution

It introduces a model with a time-dependent deceleration parameter and cosmological constant in Bianchi-V space-time, analyzing the universe's transition phases with viscous effects.

Findings

Cosmological constant remains positive and decreases over time.

The universe transitions from deceleration to acceleration.

Model aligns with supernovae observational data.

Abstract

The paper presents the transition of universe from early decelerating phase to current accelerating phase with viscous fluid and time dependent cosmological constant $(\Lambda)$ as source of matter in Bianchi-V space-time. To study the transit behaviour of universe, we have assumed the scale factor as increasing function of time which generates a time dependent deceleration parameter (DP). The study reveals that the cosmological term does not change its fundamental nature for $\xi$ = constant and $\xi=\xi(t)$, where $\xi$ is the coefficient of bulk viscosity. The $\Lambda(t)$ is found to be positive and is decreasing function of time. The same is observed by recent supernovae observations. The physical behaviour of universe has been discussed in detail.