G. S. Khadekar

STRING DUST COSMOLOGICAL MODEL IN HIGHER-DIMENSIONAL SPACE–TIME

We have investigated the bulk viscous fluid string dust cosmological model in the higher dimensional space–time. To obtain a determinate solution, it is assumed that the coefficient of bulk viscosity is a power function of the energy density τ = τcρm(t) and the scalar of expansion is proportional to shear scalar, which leads to a relation between metric potentials A = KRn where A and R are functions of time. It is also observed that models appear to be singular at and in the presence and absence of bulk viscosity and for n = 1, the model represent an isotropic universe. The physical and geometrical aspects of the model are also discussed.

Bianchi type i cosmological model with varying G, Λ & σ2 in VSL theory

Abstract In this paper we study the Bianchi type I cosmological model in the framework of variable speed of light (VSL) theory. The cosmological field equations are solved for variable G，c and Λ coupled with shear parameter σ2. It is shown for the large value of t the resulting model reduces to FLRW model with Λ approaches to constant. We also derived exact expressions for the look back time, proper distance, luminosity distance and angular diameter distance versus redshift in the framework of VSL theory as already discussed by Khadekar and Kamdi [Int. Jour. Theo. Phys. 48 314% (2009)] in different context.

Bulk viscosity in Friedmann universe with a varying speed of light described by modified equation of state

We solve the Freidmann equations by considering a universe media as a bulk viscosity described by a modified equation of state (EOS) of the form p = (γ - 1)ρc2 + Λ(t). A completely integrable dynamical equation to the scale factor is obtained and gives out the exact solution by assuming that the time-dependent parameter Λ and the bulk viscosity are linear combination of two and three terms, respectively and is expressed as:

Higher Dimensional Cosmological Model of the Universe with Time Dependent Equation of State

\Lambda(t) = \Lambda_{0} + \Lambda_{1}\frac{\dot{R}}{R}

Higher Dimensional String Cosmological Model with Dynamical Cosmological Term Λ

and

String Cosmological Model with Bulk Viscosity in Higher Dimensional Space Time

\zeta = \zeta_{0}+\zeta_{1} {\dot{R}}/{R}+\zeta_{2} {\ddot{R}}/{\dot R}

Higher Dimensional Static Cosmological Model in Lyra Manifold

, where R is a scale factor and Λ0, Λ1, ζ0, ζ1, ζ2, are constants. For a special choice of the parameters, we discuss the acceleration expansion of the universe evolution and future singularities in the framework of variable speed of light (VSL) theory.

Bianchi Type VI Cosmological Model with Varying

Abstract Higher dimensional cosmological model of the universe is obtained by assuming variable cosmological constant term Λ of the form: and Λ ~ ρ with equation of state p = f(t)ρ. Dynamical behaviors of the model for the gamma law equation of state is studied.

\Lambda

Abstract We have analysed Kaluza Klein type five dimensional cosmological model by considering three different forms of variable and Λ ~ ρ. It is found that, the connecting free parameters of the models with cosmic matter and vacuum energy density parameters are equivalent, in the context of higher dimensional space time.

Term in General Relativity

Abstract We have investigated the bulk viscous fluid string dust cosmological model in the higher dimensional space-time. To obtain a determinate solution, it is assumed that the coefficient of bulk viscosity is a power function of the scalar of expansion τ = Aθm (t) and the scalar of expansion is proportional to shear scalar, which leads to a relation between metric potentials A = KRn where A and R are function of time. It is also shown that bulk viscosity plays an important role on the evolution of the universe. The physical and geometrical aspects of the model are also discussed.