Abstract
Abstract In this paper, we have investigated the homogeneous and anisotropic Bianchi type–I cosmological model with a time-varying Newtonian and cosmological constant. We have analytically solved Einstein’s field equations (EFEs) in the presence of a stiff-perfect fluid. We show that the analytical solution for the average scale factor for the generalized Friedman equation involves the hyper-geometric function. We have studied the physical and kinematical quantities of the model, and it is found that the universe becomes isotropic at late times.
Highlights
Cosmological models with time-varying vacuum energy density Λ and Newtonian gravitational Constant have attracted the attention of several authors (Beesham 1986; Kalligas et al 1992; Carvalho et al 1992; Singh and Tiwari 2008)
In this paper, we have investigated the homogeneous and anisotropic Bianchi type−I cosmological model with a time-varying Newtonian and cosmological constant
The main objective of this paper was to find a generalized solution for Bianchi type−I cosmological model with timevarying Newtonian and Cosmological constant for a stiff perfect fluid without making any constraints on the adjustable constants of quantum field theory on curved and expanding background α and β that appears in Λ term
Summary
Cosmological models with time-varying vacuum energy density Λ and Newtonian gravitational Constant have attracted the attention of several authors (Beesham 1986; Kalligas et al 1992; Carvalho et al 1992; Singh and Tiwari 2008). Bianchi type-I universe with a self-consistent nonlinear spinor field (NLSF) and a self-consistent system of interacting spinor and scalar fields and a general NLSF in presence of perfect fluid with time-dependent gravitational constant G and cosmological constant Λ in Einstein’s equation have been used to study the initial singularity and asymptotic isotropization process by Saha (2001a,b, 2015). It has been shown that the results remain the same even in the case when the Bianchi type−I universe is filled with a perfect fluid At this stage, it is worth mentioning that most of the previously published studies on Bianchi type I, III, V and VI (Pradhan and Kumar 2001; Mazumder 1994; Ram 1989; Singh and Tiwari 2008; Arbab 1998) with a time-varying G and cosmological constant Λ.
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