Bulk Viscous LRS Biachi-I Universe with variable $G$ and decaying $\Lambda$

TL;DR

This paper develops a cosmological model of an anisotropic universe with variable gravitational and cosmological constants, showing that the model aligns well with recent supernova observations and predicts a decreasing $\Lambda$ over time.

Contribution

It introduces a new anisotropic Bianchi type I cosmological model with variable $G$ and $\Lambda$, incorporating bulk viscosity and observational consistency.

Findings

$\Lambda$ decreases over time and approaches a small positive value.

Model's distance modulus curve matches supernova observations.

Supports variable $G$ and $\Lambda$ in anisotropic cosmology.

Abstract

The present study deals with spatially homogeneous and totally anisotropic locally rotationally symmetric (LRS) Bianchi type I cosmological model with variable $G$ and $\Lambda$ in presence of imperfect fluid. To get the deterministic model of Universe, we assume that the expansion $(\theta)$ in the model is proportional to shear $(\sigma)$. This condition leads to $A=\ell B^{n}$, where $A$,\;$B$ are metric potential. The cosmological constant $\Lambda$ is found to be decreasing function of time and it approaches a small positive value at late time which is supported by recent Supernovae Ia (SN Ia) observations. Also it is evident that the distance modulus curve of derived model matches with observations perfectly.