Cosmological aspects of $f(R,T)$ gravity in a simple model with a parametrization of $q$

TL;DR

This paper investigates a cosmological model within $f(R,T)$ gravity, using a quadratic parametrization of the deceleration parameter to describe a universe transitioning from deceleration to acceleration, ultimately favoring a Big Rip fate.

Contribution

It introduces a specific quadratic $q(t)$ parametrization in $f(R,T)$ gravity and analyzes its implications for cosmic evolution and future singularity.

Findings

The model predicts a Big Rip future for the universe.

The EoS parameter exhibits singularities at initial and Big Rip phases.

Physical parameters evolve consistently with the proposed $f(R,T)$ form.

Abstract

In this paper, we have considered a quadratic variation of the deceleration parameter ($q$) as a function of cosmic time ($t$) which describes a smooth transition from the decelerating phase of the Universe to an accelerating one and also show some distinctive feature from the standard model. The logical move of this article is against the behavior of the future Universe, \textit{i.e.} whether the Universe expands forever or ends with a Big Rip, and we observe that the outcome of the considered parametrization comes in favor of Big Rip future of the Universe. The whole set up of the parametrization and solution is taken in $f(R,T)$ theory of gravity for a spatially flat Friedmann-Lema\^{\i}tre-Robertson-Walker (FLRW) geometry. Furthermore, we have considered the functional form of $f(R,T)$ function as $% f(R)+f(T)$, where a quadratic correction of the geometric term $R$ is adopted as the function $f(R)$, and a linear matter term $f(T)$. We have investigated some features of the model by examining the behavior of physical parameters. Our primary goal here is to discuss the physical dynamics of the model in $f(R,T)$ gravity. We have found, the EoS parameter also has the same singularity as that of the Hubble parameter \textit{i.e.} at the initial phase and at the Big Rip. The EoS parameter is explored in some detail for our choice of $f(R,T)$ function considered here. Different cases for $f(R,T)$ functional form for different values of the coupling parameters are discussed, and the evolution of the physical parameters is shown graphically.