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

Abstract

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.

Locally rotationally symmetric (LRS) Bianchi type II string dust viscous fluid cosmological models in Lyra geometry

“…We have attempted to explore the possibility of constructing a string dust viscous fluid cosmological model in Bianchi type II space-time with displacement vector (␤) in Lyra geometry using geometric condition shear proportional to expansion. Model (35) in the presence of bulk viscosity starts with a Big Bang at T = 0 and the expansion in the model decreases as T increases. The displacement vector, ␤, is constant initially.…”

“…Wang [34] considered locally rotationally symmetric Bianchi type II spacetime using Letelier's [6] concept for massive strings. Recently, Amirhashchi and Zeyauddin [1] and Pradhan et al [35] obtained Bianchi type II cosmological models with perfect fluid distribution and string dust, respectively. Many authors [23,[36][37][38][39][40][41] have investigated string cosmological models in the framework of Lyra geometry.…”

Bianchi type-II cosmological model: some remarks

“…In search of a realistic picture of the early Universe such models have been widely studied within a framework of General Relativity. In this note we confine our study to the scope of a Bianchi type-II (BII) space-time, which has recently been studied by a number of authors: Christodoulakis et al [1] investigated the set of space˛time general coordinate transformations which leave the line element of a generic Bianchi-type geometry quasiform invariant; Einstein's field equations for stationary BII models with a perfect fluid source were investigated by Nilsson and Uggla [2]; Ram and Singh [3] presented analytical solutions of the Einstein-Maxwell equations for cosmological models of LRS Bianchi type-II, VIII and IX; two-fluid BII cosmological models were studied by Pant and Oli [4]; a BII cosmological model with constant deceleration parameter was considered by Singh and Kumar [5]; Belinchon [6,7] studied a massive cosmic string within the scope of a BII model, while LRS BII cosmological models in the presence of a massive cosmic string and varying cosmological constant were studied by Pradhan et al [8], Kumar [9] and Yadav et al [10], respectively. Other recent work includes exact solutions for BII cosmological model in the Jordan Brans-Dicke scalar-tensor theory of gravitation were obtained in [11], study of a BII Lyttleton-Bondi Universe [12], and determination of an anisotropic BII cosmological model in the presence of source-free electromagnetic fields in Lyra's manifold [13].…”

Anisotropic Bianchi Type-II Massive String Cosmological Models with Time-Decaying Λ Term and Thermodynamic Parameters

“…Belinchon [60,61] studied Bianchi type-II space-time in connection with massive string and perfect fluid models with time varying constants under the self-similarity approach. Amirhashchi and Zainuddin [62] and Pradhan et al [63,64] have investigated LRS Bianchi type II cosmological models with perfect fluid distribution of matter and string dust in different contact. Magnetized String Cosmology in Anisotropic Bianchi-II Space-time with Variable Cosmological Term-Λ in general relativity is studied by Jotania et al [65] by considering direction of string along x-axis.…”