$f(R,T)=f(R)+λT$ gravity models as alternatives to cosmic acceleration

Abstract

This article presents cosmological models that arise in a subclass of f (R, T ) = f (R)+f (T ) gravity models, with different f (R) functions and fixed T -dependence. That is, the gravitational lagrangian is considered as f (R, T ) = f (R) + λT , with constant λ. Here R and T represent the Ricci scalar and trace of the stress-energy tensor, respectively. The modified gravitational field equations are obtained through the metric formalism for the Friedmann-Lemaître-Robertson-Walker metric with signature (+, −, −, −). We work with, with α, µ, k, γ, m and n all free parameters, which lead to three different cosmological models for our Universe. For the choice of λ = 0, this reduces to widely discussed f (R) gravity models. This manuscript clearly describes the effects of adding the trace of the energy-momentum tensor in the f (R) lagrangian. The exact solution of the modified field equations are obtained under the hybrid expansion law. Also we present the Om diagnostic analysis for the discussed models.

The study of Kantowski-Sachs perfect fluid cosmological model in modified gravity

“…• From figure 2 it is clear that volume increases with the decrease of redshift which indicates volume of the expanding universe. From equation (37), it is noticed that the shear scalar is a function of time and tends to zero when t → ∞.…”

“…Paul et al [36] have worked on accelerating universe in modified theories of gravity. Sahoo et al [37] have studied on f (R, T ) = f (R) + λT gravity models as alternatives to cosmic acceleration. Moreas and Sahoo [38] have discussed traversable wormholes by using functional form f (R, T ) = R + γe χT and also with this functional form Moreas et al [39] studied FRW cosmological model.…”