FRW viscous cosmology with inhomogeneous equation of state and future singularity

Abstract

A universe media is considered as a bulk viscosity described by inhomogeneous equation of state (EOS) of the form [Formula: see text], where [Formula: see text] is a time-dependent parameter. A generalized dynamical equation for the scale factor of the universe is proposed to describe the cosmological evolution, in which we assume the bulk viscosity and time-dependent parameter [Formula: see text] are linear combination of two terms of the form: [Formula: see text] and [Formula: see text], i.e.[Formula: see text]one is constant and other is proportional to Hubble parameter [Formula: see text]. In this framework, we demonstrate that this model can be used to explain the dark energy dominated universe, and the inhomogeneous term of specific form introduced in EOS, may lead to three kinds of fates of cosmological evolution: no future singularity, big rip or Type[Formula: see text]III singularity as presented by [S. Nojiri and S. D. Odintsov, Phys. Rev. D 72, 023003 (2005)].

FLRW viscous cosmological models

“…It is to note in comparison to the abovementioned form of Meng et al [38] that here also one is a constant, however the other is proportional to Hubble parameter H = Ṙ R and they [39] successfully discussed the accelerating expansion of the universe evolution and future singularities in the framework of general theory of relativity. We would also like to mention that Khadekar and Ghogre [49] solved the Friedmann equations analytically as well as numeri-cally in the framework of variable speed of light (VSL) theory by assuming Λ(t) = Λ 0 + Λ 1 Ṙ R (exactly as Eq.…”

“…Meng et al [38] assumed the bulk viscosity as a linear combination of two terms: one is a constant and the other is proportional to the scalar expansion θ = 3 Ṙ R and discussed evolution of the universe through accelerating expansion and future singularity for FLRW model by using EOS of the form p = (γ −1)ρ+p 0 , where p 0 is a parameter. Recently Khadekar et al [39] have solved the Friedmann equations with inhomogeneous EOS by considering bulk viscosity and time dependent parameter Λ [1][2][3][40][41][42][43][44][45][46][47][48] as linear combination of two terms in the forms:…”

Kaluza-Klein Bulk Viscous String Cosmological Model in Barber’s Second Self-Creation Theory of Gravitation

“…Many authors have studied cosmological models with the presence of bulk viscous fluid and cosmic strings coupled with scalar fields which play a vital role in the discussion of large scale structure and behaviour of the early universe. Khadekar et al [17] discussed bulk viscosity in Freedman universe with a varying speed of light described by modified equation of state. The five-dimensional Kaluza-Klein universe with bulk viscosity and cosmic strings in Brans Dicke theory has been studied by Naidu et al [18].…”

FRW Viscous Dark Fluid with Non-linear Inhomogeneous Equation of State

“…It is well known that present universe is subject to acceleration, which can be explained in terms of an ideal fluid (dark energy) with usual matter, and which has uncommon equation of state. Khadekar et al [5], consider the effect of dark energy model with inhomogeneous equation of state of the form p = (γ − 1)ρ + Λ(t) and proposed dynamical generalized scale factor for the universe in which they assume the bulk viscosity ζ and time dependent parameter Λ as a linear combination of two terms: one is proportional to constant and other is proportional to scalar expansion θ. In continuation of this work recently Khadekar and Deepti [3] obtained the solutions of the field equations by using the above inhomogeneous equation of state with equation of state parameter ω is constant and is a function of ρ.…”