A Transition Model in f(R,T) Theory via Observational Constraints

Abstract

A particular form of the time-dependent deceleration parameter is used to examine the accelerated expansion of the universe and the phase transition in this expansion in the context of f(R,T) gravity theory for the flat FRW model. The modified field equations are solved under the choice of f(R,T)=R+2f(T). The best fit values of the model parameters that would be consistent with the recent observational datasets that are estimated. For this estimation, 57 points from Cosmic Chronometers (CC) datasets and 1048 points from Pantheon supernovae datasets are used. Bayesian analysis and likelihood function are applied together with Markov Chain Monte Carlo (MCMC) method at 1σ and 2σ confidence levels. Then, the physical behavior of parameters such as density, pressure and cosmographic parameters corresponding to these constrained values of the model parameters are analyzed. Looking at the deceleration parameter, it is seen that the universe has passed from a decelerating expansion phase to an accelerating phase. As a result, it has been shown that the cosmological model f(R,T) that we discussed can explain the accelerating expansion of the late universe well without resorting to any dark energy component in the energy-momentum tensor.