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Author: search.filters.author.Pradhan, AnirudhSubject: search.filters.subject.Cosmology

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    A new class of LRS Bianchi Type –I cosmological models in lyra geometry
    (2015-03-01) Pradhan, Anirudh; Vishwakarma, Anil Kumar
    LRS Bianchi type-1 models have been studied in the cosmological theory based on Lyra's geometry. A new class of exact solutions has been obtained by considering a time dependent and constant displacement field for constant deceleration parameter models of the universe. The physical behaviour of the models is examined in vacuum and in the presence of perfect fluids.
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    Nonsingular spherical models with a variable cosmological term
    (2011-07-06) Pradhan, Anirudh; Srivastava, Kashika; Lal, Amrit
    Exact solutions of the Einstein’s field equations describing a spheri- cally symmetric cosmological model without a big bang or any other kind of singularity recently obtained by Dadhich and Patel (2000) are revis- ited. The matter content of the model is a shear-free perfect fluid with isotropic pressure and a radial heat flux. Three different exact solutions are obtained for both perfect fluid and fluid with bulk viscosity. It turns out that the cosmological rerm Λ(t) is a decreasing function of time, which is consistent with recent observations of type Ia supernovae.
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    Universe with time dependent deceleration parameter and /\ term in general relativity
    (2006-07-28) Pradhan, Anirudh; Otarod, Saeed
    A new class of exact solutions of Einstein’s field equations with perfect fluid for an LRS Bianchi type-I spacetime is obtained by using a time dependent deceleration parameter. We have obtained a general solution of the field equations from which three models of the universe are derived: exponential, polynomial and sinusoidal form respectively. The behaviour of these models of the universe are also discussed in the frame of reference of recent supernovae Ia observations.
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    Plane symmetric inhomogeneous bulk viscous domain wall in Lyra geometry
    (2005-07-01) Pradhan, Anirudh; Rai, Vandana; Otarod, Saeed
    Some bulk viscous general solutions are found for domain walls in Lyra geometry in the plane symmetric inhomogeneous spacetime. Expressions for the energy density and pressure of domain walls are derived in both cases of uniform and time varying displacement field β. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density. Some physical consequences of the models are also given. Finally, the geodesic equations and acceleration of the test particle are discussed.
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    Kaluza-Klein Type Robertson Walker Cosmological Model With Dynamical Cosmological Term Lambda
    (2005-12-01) Pradhan, Anirudh; Khadekar, G. S.; Patki, Vrishali
    In this paper we have analyzed the Kaluza-Klein type RobertsonWalker (RW) cosmological models by considering three different forms of variable Λ: Λ ∼˙ a a 2 , Λ ∼ ¨ a a 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. The expression for the look back time, luminosity distance and angular diameter distance are also derived. This work has thus generalized to higher dimensions the well-known results in four dimensional space time. It is found that there may be significant difference in principle at least, from the analogous situation in four dimensional space time.