Effective equation of state in modified gravity and observational constraints

Abstract

In this article, the bulk viscosity is introduced in a modified gravity model. The gravitational action has a general $f(R,T)$ form, where $R$ and $T$ are the curvature scalar and the trace of energy momentum tensor respectively. An effective equation of state (EoS) has been investigated in the cosmological evolution with bulk viscosity. In the present scenario, the Hubble parameter which has a scaling relation with the redshift can be obtained generically. The role of deceleration parameter $q$ and equation of state parameter $\omega$ is discussed to explain the late-time accelerating expansion of the universe. The statefinder parameters and Om diagnostic analysis are discussed for our obtained model to distinguish from other dark energy models together with the analysis of energy conditions and velocity of sound for the model. We have also numerically investigated the model by detailed maximum likelihood analysis of $580$ Type Ia supernovae from Union $2.1$ compilation datasets and updated $57$ Hubble datasets ($31$ data points from differential age method and $26$ points from BAO and other methods). It is with efforts found that the present model is in good agreement with observations.

arXiv commentCQG accepted version

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• Bulk viscous matter and the cosmic acceleration of the universe in $f(Q,T)$ gravity
• Observational constraints and some toy models in $f(Q)$ gravity with bulk viscous fluid
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• Cosmic Evolution of the Kantowski-Sachs Universe in the Context of a Bulk Viscous String in Teleparallel Gravity
• Charged Gravastar Solutions in the Finch-Skea Framework with f(\mathbb{Q}) Gravity