Energy conditions in non‐minimally coupled f(R, T) gravity

Abstract

In today's scenario, going beyond Einstein's theory of gravity leads us to some more complete and modified gravity theories. One of them is the f (R, T) gravity in which R is the Ricci scalar, and T is the trace of the energy-momentum tensor. Using a well-motivated linear f (R, T) gravity model with a single parameter, we studied the strong energy condition (SEC), the weak energy condition (WEC), the null energy condition (NEC), and the dominant energy condition (DEC) under the simplest non-minimal matter geometry coupling with a perfect fluid distribution. The model parameter is constrained by energy conditions and a single-parameter proposed equation of state (EoS), resulting in the compatibility of the f (R, T) models with the accelerated expansion of the universe. It is seen that the EoS parameter illustrates the quintessence phase in a dominated accelerated phase, pinpoint to the cosmological constant yields as a prediction the phantom era. Also, the present values of the cosmological constant and the acceleration of the universe are used to check the viability of our linear f (R, T) model of gravity. It is observed that the positive behavior of DEC and WEC indicates the validation of the model. In contrast, SEC is violating the condition resulting in the accelerated expansion of the universe.

Cosmological dynamics in f(R) gravity models through cosmographic energy conditions

“…These conditions are obtained from the well-known Raychaudhuri's equations and the requirement that gravity be attractive. The Raychaudhuri's equations are provided in the following forms for congruence of time-like and null-like geodesics in a spacetime manifold supplied with a metric g μν [23][24][25][26][27][28].…”

Evolution of gravitational waves in non-minimal coupling between geometry and matter theories of gravity

“…Due to the coupling of matter and geometry, the cosmic speed-up in this modified theory results from the geometrical contribution and the matter content. A lot of research has been carried out into astrophysical and cosmological aspects of this theory, such as thermodynamics, wormhole solutions, gravitational waves, energy conditions, and so on [29][30][31][32][33][34][35][36][37][38][39][40].…”

A measure of complexity for axial self-gravitating static fluids

“…The f (R) theory is the simplest extension to GR, based on the replacement of the curvature invariant R in the EH action by its general function f (R), demonstrating cosmic rapid expansion [17][18][19][20][21]. In the previous few years, the researchers presented various cosmological frameworks that might help to explain inflation and other constituents of the Universe that are still mysteries [22][23][24][25][26][27][28]. This approach has distinct formulations to deduce the field equations: (i) The first approach is metric formulation (metric f (R) theory) in which the fourth-order field equations are inferred by varying the generic action with metric tensor g α ν .…”