Cosmological models of universe with variable deceleration parameter in Lyra's manifold

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The present study deals with locally rotationally symmetric (LRS) Bianchi type II cosmological model representing massive string. The energy-momentum tensor for such string as formulated by Letelier (Phys. Rev. D 28:2414, 1983) is used to construct massive string cosmological model for which we assume that the expansion (θ ) in the model is proportional to the shear (σ ). This condition leads to A = B m , where A and B are the metric coefficients and m is proportionality constant. For suitable choice of constant m, it is observed that in early stage of the evolution of the universe string dominates over the particle whereas the universe is dominated by massive string at the late time. Our model is in accelerating phase which is consistent to the recent observations of type Is supernovae. Some physical and geometric behavior of the model is also discussed.

Section: Introductionmentioning

confidence: 99%

LRS Bianchi type-II massive string cosmological model in General Relativity

Pradhan

Ram

Singh³

2010

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“…He pointed out that the displacement vector φ i plays the role of cosmological constant in the normal relativistic treatment. Recently, many authors have investigated several cosmological models within the framework of Lyra geometry (Pradhan et al 2006;Rahaman et al 2002;Mohanty et al 2009). Katore and Hatkar (2015) studied magnetized anisotropic dark energy in the context of general relativity and Lyra geometry.…”

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confidence: 99%

Strange quark matter coupled to string cloud in Lyra geometry

Katore

Hatkar

2015

Hypersurface homogeneous cosmological models for strange quark matter coupled to string cloud in the framework of Lyra geometry have been presented. Exact solution of the field equations are obtained by considering various forms of the deceleration parameter found in the literature. It is observed that the rest energy density, particle energy density and string tension density are affected by displacement vector β. Physical parameters of the investigated model are also discussed.

“…Yadav et al (2007aYadav et al ( , 2007b have obtained the integrability of cosmic string in Bianchi type III space-time in presence of bulk viscous fluid by applying a new technique. Reddy (2003, , , Rao et al (2008aRao et al ( , 2008bRao et al ( , 2009), Rao and Vinutha (2010), Pradhan (2007Pradhan ( , 2009), Pradhan and Mathur (2008) and Pradhan et al ( , 2010aPradhan et al ( , 2010b have studied string cosmological models in different contexts. Recently, Belinchon (2009aBelinchon ( , 2009b, Pradhan et al (2009), Amirhashchi andZainuddin (2010) and Tripathi et al (2009Tripathi et al ( , 2010 have obtained cosmic strings in different Bianchi type spacetimes.…”

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confidence: 99%

Anisotropic Bianchi type-I models in string cosmology

Pradhan¹,

Chouhan

2010

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The present study deals with a spatially homogeneous and anisotropic Bianchi-I cosmological models representing massive strings. The energy-momentum tensor, as formulated by Letelier (1983), has been used to construct massive string cosmological models for which we assume the expansion scalar in the models is proportional to one of the components of shear tensor. The Einstein's field equations have been solved by applying a variation law for generalized Hubble's parameter in Bianchi-I space-time. We have analysed a comparative study of accelerating and decelerating models in the presence of string scenario. The study reveals that massive strings dominate in the decelerating universe whereas strings dominate in the accelerating universe. The strings eventually disappear from the universe for sufficiently large times, which is in agreement with current astronomical observations.