Cosmological Evolution in the Background of Non-Minimally Coupled Gravity

Abstract

In current cosmic scenario, an accelerated expansion era is being reported by various observations. The reasoning of such scenario is still unknown, the pres- ence of an unknown energy component is seen which is named as DE. There are various approaches to discuss the existence of DE and present acceleration of universe. One of such attempts is the modification of Einstein’s gravity, here we attempt to explore this problem within the modified gravity based on non- minimal matter-geometry coupling. We examine f(R, T,Q) theory (where R is the Ricci Scalar, T is the trace of EMT Tuv and Q = RuvTuv is interaction of EMT Tμν and Ricci Tensor Ruv). We formulate the dynamical equations in the back- ground of FLRW model and find the result of non-conserved EMT using the divergence of the field equations. In this scenario test particles deviates from geodesic motion and an extra force is there due to non-minimal coupling. We applied this result to find an expression for energy density ρ for particular choice of Lagrangian. Furthermore, we discuss the energy bound on the model param- eters and discuss the late time cosmic acceleration for best suitable parameters in accordance with recent observations. We also study the cosmic evolution of non-minimally coupled f(R, T) gravity (where R stands for Ricci scalar and T for trace of EMT) with matter formed of CM and radiations. We find the cosmic evolution in the background of CM and compare the results with NCM and ΛCDM model. In this study, we consider the flat FLRW metric and formulate the dynamical equations. Here, we choose two models of non-minimal coupled f(R, T) gravity (already reconstructed in [1]), and discuss the evolution of cosmological parameters, the effective EoS ωeff and the deceleration parameter q(z) in the universe containing self-interacting CM and radiations. In graphical description of these parameters we establish the comparison of results for self-interacting CM, NCM and ΛCDM model. Our results are consistent with the observational data.