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In this paper we have considered an anisotropic space-time model of the Universe in presence of Brans-Dicke (BD) scalar field $\phi$, causal viscous fluid and barotropic fluid. We have shown that irrespective of fluid the causality theory…

General Relativity and Quantum Cosmology · Physics 2011-09-27 Shuvendu Chakraborty , Ujjal Debnath

We present a family of spherically symmetric multi-horizon spacetimes with a vacuum dark fluid, associated with a time-dependent and spatially inhomogeneous cosmological term. The vacuum dark fluid is defined in a model-independent way by…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Kirill Bronnikov , Irina Dymnikova , Evgeny Galaktionov

We consider a self-consistent system of Bianchi type-I (BI) gravitational field and a binary mixture of perfect fluid and dark energy. The perfect fluid is taken to be the one obeying the usual equation of state, i.e., $p = \zeta \ve$, with…

General Relativity and Quantum Cosmology · Physics 2015-05-01 Bijan Saha

In this letter, it is obtained using dual role of the Ricci scalar (physical as well as geometrical role of the Ricci scalar curvature) in a natural way without any input in the theory for it. In contrast to other models, where an idea for…

Astrophysics · Physics 2007-05-23 S. K. Srivastava

The dark sector of the Universe need not be completely separable into distinct dark matter and dark energy components. We consider a model of early dark energy in which the dark energy mimics a dark matter component in both evolution and…

Cosmology and Nongalactic Astrophysics · Physics 2014-09-05 Jannis Bielefeld , Robert R. Caldwell , Eric V. Linder

We investigate the evolution of a spatially flat Friedmann-Robertson-Walker (FRW) universe in the framework of scalar non-metricity theory of gravity. In the model, we consider dark matter (DM) and dark energy (DE) described by the scalar…

General Relativity and Quantum Cosmology · Physics 2025-08-05 Bikash Chandra Roy , Bikash Chandra Paul

In this paper, we investigate the behavior of equation of state parameter and energy density for dark energy in the framework of f(T) gravity. For this purpose, we use anisotropic LRS Bianchi type I universe model. The behavior of…

General Relativity and Quantum Cosmology · Physics 2015-06-15 M. Sharif , Sehrish Azeem

We study the anisotropic and homogeneous Bianchi type-V Universe with holographic dark energy (HDE) and interacting dark matter (DM). The solution for the field equations have been obtained for a certain form of the deceleration parameter.…

General Relativity and Quantum Cosmology · Physics 2025-07-29 Gunjan Varshney , Anirudh Pradhan , Nasr Ahmed , Vansh Mittal

We study the behaviour of Bianchi class A universes containing an ultra-stiff isotropic ghost field and a fluid with anisotropic pressures which is also ultra-stiff on the average. This allows us to investigate whether cyclic universe…

General Relativity and Quantum Cosmology · Physics 2016-05-25 John D. Barrow , Chandrima Ganguly

We examine the anisotropy originated from a first-order vacuum phase transitions through three-dimensional numerical simulations. We apply Bianchi Type-I metric to our model that has one scalar field minimally coupled to the gravity. We…

General Relativity and Quantum Cosmology · Physics 2023-08-01 A. Savaş Arapoğlu , A. Emrah Yükselci

Gravitational collapse of a spherically symmetric homogeneous perfect barotropic fluid with linear as well as polytropic type Equation of State (EoS) has been investigated in the framework of a linear model of $f(R,T)$ gravity. This…

General Relativity and Quantum Cosmology · Physics 2020-05-06 Karim Mosani , Gauranga C. Samanta

In this study, we deviate from the traditional examination of the evolving universe through the scale factor and instead consider a parameter \(\chi_{ME}\), defined by the ratio of two competing energy densities: matter (DM) and dynamic…

General Relativity and Quantum Cosmology · Physics 2024-11-04 Bob Osano

A model for the late-time accelerated expansion of the universe is considered where a van der Waals fluid interacting with matter plays the role of dark energy. The transition towards this phase in the cosmic evolution history is discussed…

General Relativity and Quantum Cosmology · Physics 2018-03-28 E. Elizalde , M. Khurshudyan

The paper deals with a spatially homogeneous and isotropic FRW space-time filled with perfect fluid and dark energy components. The two sources are assumed to interact minimally, and therefore their energy momentum tensors are conserved…

General Relativity and Quantum Cosmology · Physics 2014-08-21 Suresh Kumar

In view of late-time cosmic acceleration, a dark energy cosmological model is revisited wherein Einstein's cosmological constant is considered as a candidate of dark energy. Exact solution of Einstein field equations (EFEs) is derived in a…

General Relativity and Quantum Cosmology · Physics 2019-11-22 S. K. J. Pacif , Md Salahuddin Khan , L. K. Paikroy , Shalini Singh

We study the cosmological evolution based upon a $D$-dimensional action in low-energy effective string theory in the presence of second-order curvature corrections and a modulus scalar field (dilaton or compactification modulus). A…

High Energy Physics - Theory · Physics 2009-11-11 Gianluca Calcagni , Shinji Tsujikawa , M Sami

In this work, we investigate the cosmological dynamics of an anisotropic Universe within the framework of $f(R,T)$ gravity by incorporating pressureless dark matter and the dark energy models. The analysis is carried out in a Bianchi type-I…

General Relativity and Quantum Cosmology · Physics 2026-05-13 S. H. Shekh , N. Myrzakulov , Anirudh Pradhan , M. Zeyauddin

Within the framework of spatially covariant theories, we propose a general model for dark energy (DE) in which the cosmological background and perturbations are independently controlled by different sets of coefficients, and the equation of…

General Relativity and Quantum Cosmology · Physics 2025-08-05 Zhibang Yao , Gen Ye , Alessandra Silvestri

In this study, we have explored a scalar field cosmological model in the axially symmetric Bianchi type-I universe. In this study, our aim is to constrain the scalar field dark energy model in an anisotropic background. For this purpose,…

General Relativity and Quantum Cosmology · Physics 2025-11-19 Vinod Kumar Bhardwaj , Anil Kumar Yadav

We study in detail the phase space of a Friedmann-Robertson-Walker Universe filled with various cosmological fluids which may or may not interact. We use various expressions for the equation of state, and we analyze the physical…

General Relativity and Quantum Cosmology · Physics 2017-09-13 S. D. Odintsov , V. K. Oikonomou , Petr V. Tretyakov
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