Viscous cosmology in the Weyl-type $f(Q,T)$ gravity

TL;DR

This paper explores how bulk viscosity influences the universe's evolution within Weyl-type $f(Q,T)$ gravity, deriving exact solutions, constraining parameters with observational data, and analyzing cosmic acceleration transitions.

Contribution

It introduces a viscous cosmological model in Weyl-type $f(Q,T)$ gravity with a specific viscosity coefficient, providing exact solutions and observational constraints.

Findings

Model aligns well with Hubble and Pantheon datasets.

Universe transitions from deceleration to acceleration under certain parameters.

Exact solutions demonstrate the impact of bulk viscosity on cosmic dynamics.

Abstract

Bulk viscosity is the only viscous influence that can change the background dynamics in a homogeneous and isotropic universe. In the present work, we analyze the bulk viscous cosmological model with the bulk viscosity coefficient of the form $\xi=\xi_0+\xi_1H+\xi_2\left(\frac{\dot{H}}{H}+H\right)$ where, $\xi_0$, $\xi_1$ and $\xi_2$ are bulk viscous parameters, and $H$ is the Hubble parameter. We investigate the impact of the bulk viscous parameter on dynamics of the universe in the recently proposed Weyl type $f(Q, T)$ gravity, where $Q$ is the non-metricity, and $T$ is the trace of the matter energy-momentum tensor. The exact solutions to the corresponding field equations are obtained with the viscous fluid and the linear gravity model of the form $f(Q, T)=\alpha Q+\frac{\beta}{6\kappa^2}T$, where $\alpha$ and $\beta$ are model parameters. Further, we constrain the model parameters using the $57$ points Hubble dataset and recently released 1048 points Pantheon sample, which shows our model is good congeniality with observations. We study the possible scenarios and the evolution of the universe through the deceleration parameter, the statefinder diagnostics, the Om diagnostics. It is observed that the universe exhibits a transition from a decelerated to an accelerated phase of the universe under certain constraints of model parameters.