Bayesian analysis of bulk viscous matter dominated universe

TL;DR

This paper compares a bulk viscous matter universe model with the standard Lambda-CDM model using Bayesian analysis, finding the viscous model slightly better but not conclusively superior.

Contribution

It introduces a Bayesian comparison of a generalized bulk viscous universe model against Lambda-CDM, highlighting its viability and marginal advantages.

Findings

Viscous model reasonably describes universe evolution.

Bayes factor shows slight preference for viscous model.

Model not conclusively superior to Lambda-CDM.

Abstract

In our previous works, we have analyzed the evolution of bulk viscous matter dominated universe with a more general form for bulk viscous coefficient, $\zeta=\zeta_{0}+\zeta_{1}\frac{\dot{a}}{a}+\zeta_{2}\frac{\ddot{a}}{\dot{a}}$ and also carried out the dynamical system analysis. We found that the model reasonably describes the evolution of the universe if the viscous coefficient is a constant. In the present work we are contrasting this model with the standard $\Lambda$CDM model of the universe using the Bayesian method. We have shown that, even though the viscous model gives a reasonable back ground evolution of the universe, the Bayes factor of the model indicates that, it is not so superior over the $\Lambda$CDM model, but have a slight advantage over it.