Bianchi Type V Universe with Time Varying Cosmological Constant and Quadratic Equation of State in f(R,T) Theory of Gravity

Abstract

In recent years, modified theories of gravity have been extensively studied because of the discovery and confirmation of the current phase of accelerated expansion of the universe. The f(R,T) theory of gravity is one such theory, proposed by Harko et al. in 2011, in which R is the Ricci scalar and T is the trace of the stress-energy tensor. In this paper, we study Bianchi type V universe in f(R,T) theory of gravity with time varying cosmological constant and a quadratic equation of state p=αρ2-ρ, where α≠0 is a constant. We obtain exact solutions of the field equations for two cases: one with a volumetric expansion law and the other with an exponential expansion law. The physical features of the two models are discussed by examining the behaviour of some important cosmological parameters such as the Hubble parameter, the deceleration parameter etc. We find that the models have initial singularity and the physical parameters diverge at the initial epoch. The model 1, corresponding to the volumetric expansion law does not resemble ΛCDM model while the model 2, corresponding to the exponential expansion law, resembles ΛCDM model. The energy conditions of the models are also examined and found to be consistent with recent cosmological observations.

Keywords

• bianchi type v universe
• f(r,t) theory of gravity
• equation of state
• λcdm model