Contrasting the bulk viscous model with the standard $\Lambda$CDM using Bayesian statistics

TL;DR

This paper compares a bulk viscous cosmological model with the standard $$CDM model using Bayesian statistics and observational data, finding strong evidence favoring $$CDM.

Contribution

It introduces a causal bulk viscous model with a specific viscosity form and evaluates its viability against $$CDM using Bayesian inference with Pantheon data.

Findings

Bayesian analysis favors $$CDM over the viscous model.

The likelihood calculations show very strong evidence for $$CDM.

The model parameters were constrained using the latest observational data.

Abstract

Causal dissipative model is a plausible choice to explain the late accelerated epoch of universe. At the same time $\Lambda$CDM is considered to be standard model to explain the cosmological data corresponding to the late evolution of the universe. We consider a bulk viscus model in which the dissipation is driven by the bulk viscosity $\zeta=\alpha \rho^{1/2}$, described using the full causal Israel-Stewart theory. We computed the model parameters using the latest observational data (Pantheon). We contrasted this model with $\Lambda$CDM model for the late accelerated phase using Bayesian inference method. The Bayes factor has been obtained by calculating the likelihood for Pantheon data. Suitable prior values has been assumed for model parameters for calculating the likelihood. It shows that the evidence for $\Lambda$CDM against this viscous model is very strong according to Jeffrey's scale.