Constraining dark energy equations of state in $F(R,T)$ gravity

TL;DR

This study investigates the acceleration of the universe in a modified gravity model, constrains its parameters using observational data, and compares its fit to the standard cosmological model, revealing a recent transition to acceleration and phantom-like dark energy.

Contribution

It introduces a specific $F(R,T)$ gravity model, constrains its parameters with observational data, and compares its performance to $\\Lambda$CDM using statistical criteria.

Findings

Universe transitioned from deceleration to acceleration recently.

Dark energy exhibits phantom behavior in the models.

Model fits observational data comparably to $\\Lambda$CDM.

Abstract

In this paper, we examine the acceleration of the Universe's expansion in $F(R,T)$ gravity, where $R$ denotes the Ricci scalar and $T$ the trace of energy-momentum tensor. Indeed, the unknown nature of the source controlling this acceleration in general relativity leads scientists to investigate its properties by means of some alternative theories to general relativity. Our study is restricted to the particular case where $F(R,T)=R+2\kappa^2 \lambda T$ , with $\lambda$ being a constant. We use a Bayesian analysis of current observational datasets, including the type Ia supernovae constitution compilation and $H(z)$ measurements, to constrain free parameters of the model. To parametrize dark energy, we consider two well known equations of state. We find the best fit values for each model by running a Markov chain Monte Carlo technic. The best fit parameters are used to compare both models to $\Lambda$CDM by means of the Akaike information criterion and the Bayesian information criterion. We show that the Universe underwent recently a transition from a deceleration to an acceleration for both models. Furthermore, the data shows a phantom nature of the equation of state for both models.