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Bianchi type V string cosmological models with bulk viscosity for massive string are investigated. The bulk viscosity is assumed to vary with time in such a manner that it is related to simple power function of the energy density. Using…

General Relativity and Quantum Cosmology · Physics 2011-09-28 Anil Kumar Yadav

An LRS Bianchi type-V cosmological models representing a viscous fluid distribution with a time dependent cosmological term $\Lambda$ is investigated. To get a determinate solution, the viscosity coefficient of bulk viscous fluid is assumed…

General Relativity and Quantum Cosmology · Physics 2007-08-06 Anirudh Pradhan , J. P. Shahi , C. V. Singh

Bianchi-type string cosmology involves generalizations of the FRW backgrounds with three transitive spacelike Killing symmetries, but without any a priori assumption of isotropy in the 3D sections of homogeneity. With emphasis on those…

High Energy Physics - Theory · Physics 2009-10-28 N. A. Batakis

We consider a late-time cosmological model based on a recent proposal that the infinite-bare-coupling limit of superstring/M-theory exists and has good phenomenological properties, including a vanishing cosmological constant, and a…

General Relativity and Quantum Cosmology · Physics 2009-11-07 M. Gasperini , F. Piazza , G. Veneziano

In this paper, we have constructed dark energy models in an anisotropic Bianchi-V space-time and studied the role of anisotropy in the evolution of dark energy. We have considered anisotropic dark energy fluid with different pressure…

General Physics · Physics 2017-10-25 B. Mishra , Pratik P. Ray , S. K. J. Pacif

In this paper, we present a model of transitioning universe with minimal interaction between perfect fluid and anisotropic dark energy in Bianchi I space-time. The two sources are assumed to minimally interacted and therefore their energy…

General Relativity and Quantum Cosmology · Physics 2016-08-19 Anil Kumar Yadav

We investigate a new class of LRS Bianchi type-II cosmological models by revisiting in the paper of Mishra {\it et al} (2013) by considering a new deceleration parameter (DP) depending on the time in string cosmology for the modified…

General Physics · Physics 2021-08-02 Archana Dixit , Rashid Zia , Anirudh Pradhan

We explore the possibility that our universe's current accelerated expansion is explained by a quintessence model with an exponential scalar potential, $V =V_0\, e^{-\lambda\, \phi}$, keeping an eye towards $\lambda \geq \sqrt{2}$ and an…

High Energy Physics - Theory · Physics 2024-08-21 David Andriot , Susha Parameswaran , Dimitrios Tsimpis , Timm Wrase , Ivonne Zavala

The present study deals with a spatially homogeneous and anisotropic Bianchi-II cosmological models representing massive strings in normal gauge for Lyra's manifold by applying the variation law for generalized Hubble's parameter that…

General Physics · Physics 2012-04-13 Shilpi Agarwal , R. K. Pandey , Anirudh Pradhan

We consider the dynamics of a causal bulk viscous cosmological fluid filled constantly decelerating Bianchi type I space-time. The matter component of the Universe is assumed to satisfy a linear barotropic equation of state and the state…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. K. Mak , T. Harko

The asymptotic behaviour of two classes of scalar field cosmological models are studied using the theory of dynamical systems: general relativistic Bianchi models containing matter and a scalar field with an exponential potential and a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Andrew P. Billyard

In string gas cosmology, the extra dimensions of the underlying theory are kept at a microscopic scale by a gas of strings. In the matter-dominated era, however, dust pressure can lead to oscillations of the extra dimensions and to…

High Energy Physics - Theory · Physics 2009-11-05 Francesc Ferrer

In this paper, we investigate Bianchi type$-V$ cosmological models with bulk viscous fluid and time varying cosmological $\Lambda$ and Newtonian $G$ parameters. The Einstein's field equations have been transformed into a coupling…

It is obtained that dark energy emerges from higher-derivative gravity with anon-linear terms proportional to $R^2$ and $R^3$ with $R$ being the Ricci scalar curvature. Interestingly, it is found that the universe begins with acceleration,…

Astrophysics · Physics 2008-11-26 S. K. Srivastava

We have investigated the cosmological scenarios with a four dimensional effective action which is connected with multidimensional, supergravity and string theories. The solution for the scale factor is such that initially universe undergoes…

General Relativity and Quantum Cosmology · Physics 2014-11-17 A. A. Sen , S. Sen

We study string dynamics in the early universe. Our motivation is the proposal of Brandenberger and Vafa, that string winding modes may play a key role in decompactifying three spatial dimensions. We model the universe as a homogeneous but…

High Energy Physics - Theory · Physics 2014-11-18 Richard Easther , Brian R. Greene , Mark G. Jackson , Daniel Kabat

In this paper, we study anisotropic Bianchi-V universe with magnetic field and bulk viscous fluid in string cosmology. Exact solutions of the field equations are obtained by using the equation of state for a cloud of strings, and a…

General Relativity and Quantum Cosmology · Physics 2012-11-28 C. P. Singh , Vijay Singh

We use the dynamical analysis to study the evolution of the universe at late time for the model in which the interaction between dark energy and dark matter is inspired by disformal transformation. We extend the analysis in the existing…

General Relativity and Quantum Cosmology · Physics 2017-06-06 Khamphee Karwan , Stharporn Sapa

Bianchi type I massive string cosmological model with magnetic field of barotropic perfect fluid distribution through the techniques used by Latelier and Stachel, is investigated. To get the deterministic model of the universe, it is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Raj Bali , Umesh Kumar Pareek , Anirudh Pradhan

Bianchi type V string cosmological models in general relativity are investigated. To get the exact solution of Einstein's field equations, we have taken some scale transformations followed by Camci $\it et ~ al$ (2001). It is shown that…

General Relativity and Quantum Cosmology · Physics 2011-06-07 Anil Kumar Yadav , Vineet Kumar Yadav , Lallan Yadav