Abstract
We study an interesting alternative of modified gravity theory, namely, the unimodular f(R, T) gravity in which R is the Ricci scalar and T is the trace of the stress–energy tensor. We study the viability of the model by using the energy conditions. We discuss the strong, weak, null and dominant energy conditions in terms of deceleration, jerk and snap parameters. We investigate energy conditions for reconstructed unimodular f(R, T) models and give some constraints on the parametric space of the model. We observe that by setting appropriately free parameters, energy conditions can be satisfied. Furthermore, we study the stability of the solutions in perturbations framework. In this case, we investigate stability conditions for de Sitter and power law solutions and we examine viability of cosmological evolution of these perturbations. The results show that for some values of the input parameters, for which energy conditions are satisfied, de Sitter and power-law solutions may be stable.
Highlights
Unimodular gravity is an alternative theory of the gravitational theories which solve the cosmological constant problem [29]
An interesting result is that unimodular gravity is classically equivalent to general relativity, there is a discussion about this equivalence at the quantum level
In this work we have studied a modified gravity theory namely unimodular f (R, T ) gravity which is an alternative theory to explain the current cosmic acceleration without introducing the exotic component of dark energy or extra dimension
Summary
Unimodular gravity is an alternative theory of the gravitational theories which solve the cosmological constant problem [29]. An interesting feature of this model is that it can be explained the current expansion of the universe by considering only single component such as the cosmological constant, or by the nonrelativistic matter t[h3e1,m32et]r.iTch√e−tegchtnoibqeuea of the theory is that the fixed number, or some determinant of function of the space-time coordinates The extension of this model to the modified gravity is discussed in Refs. We consider some specific models of unimodular f (R, T ) gravity and show that for some values of input parameters, the stability of solutions are realized Through this way and analyzing the energy conditions we can check the viability of cosmological solutions in this kind of extended theory of gravity.
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