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There are evidences that the cosmic microwave background (CMB) large-angle anomalies imply a departure from statistical isotropy and hence from the standard cosmological model. We propose a LCDM model extension whose dark energy component…

Astrophysics · Physics 2008-11-26 Davi C. Rodrigues

The dark energy models with variable equation of state parameter $\omega$ is investigated by using law of variation of Hubble's parameter that yields the constant value of deceleration parameter. The equation of state parameter $\omega$ is…

General Relativity and Quantum Cosmology · Physics 2011-02-01 Anil Kumar Yadav , Farook Rahaman , Saibal Ray

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

A simple speed-up cosmology model is proposed to account for the dark energy puzzle. We condense contributions from dark energy and curvature term into one effective parameter in order to reduce parameter degeneracies and to find any…

Astrophysics · Physics 2007-10-10 Xin-He Meng , Meng Su , Zheng Wang

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 consider new models of dark energy with finite time future singularities, by introducing the pressure density as a function of the scale factor. This approach gives acceptable phenomenological models of dark energy, practically…

General Relativity and Quantum Cosmology · Physics 2019-07-17 L. N. Granda

In this paper, we have investigated an anisotropic cosmological model in $f(Q)$ gravity with string fluid in LRS Bianchi type-I universe. We have considered the arbitrary function $f(Q)=Q+\alpha\sqrt{~Q}+2\Lambda$ where $\alpha$ is model…

General Relativity and Quantum Cosmology · Physics 2023-03-02 Dinesh Chandra Maurya , Archana Dixit , Anirudh Pradhan

In this investigation we discuss the dynamical aspects of Kaluza-Klein FRW type cosmological model in the presence of dark energy fluid and an attractive massive scalar field. The field equations are solved using a power law between the…

General Physics · Physics 2019-11-07 D. R. K. Reddy , K. Deniel Raju

We study the equations for the evolution of cosmological perturbations in $f\left(\mathcal{R}\right)$ and conclude that this modified gravity model can be expressed as a dark energy fluid at background and linearised perturbation order. By…

Cosmology and Nongalactic Astrophysics · Physics 2016-02-17 R. A. Battye , B. Bolliet , J. A. Pearson

The field equations of Brans-Dicke gravity coupled to a mass-varying vector field are derived. Anisotropic cosmological solutions with a locally rotationally symmetric Bianchi type I metric and time-dependent scalar and electric vector…

General Relativity and Quantum Cosmology · Physics 2014-02-05 Ozgur Akarsu , Tekin Dereli , Neslihan Oflaz

Anisotropic dark energy cosmological models are constructed in the frame work of generalised Brans-Dicke theory with a self interacting potential. Wet dark fluid characterized by a linear equation of state is considered as the source of…

General Physics · Physics 2017-05-10 Sunil K. Tripathy , Dipanjali Behera , Bivudutta Mishra

We constrain the parameters of dynamical dark energy in the form of a classical scalar field with barotropic equation of state jointly with other cosmological parameters using various combined datasets including the CMB power spectra from…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-20 Olga Sergijenko , Bohdan Novosyadlyj

The current paper provides a comprehensive examination of a dark energy cosmological model in the classical regime, in which a generic scalar field is regarded as a dark energy source. Einstein's field equations are solved in model…

General Relativity and Quantum Cosmology · Physics 2022-09-07 Ritika Nagpal , Shibesh Kumar Jas Pacif , Abhishek Parida

This manuscript investigate the dark energy Bianchi type-I cosmological models in presence of generalized Chaplygin gas, variable gravitational and cosmological constants. In this manuscript, exact solutions of Einstein field equations are…

General Relativity and Quantum Cosmology · Physics 2022-02-11 N. Hulke , G. P. Singh , Binaya K Bishi

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

We study the consequences of a homogeneous dark energy fluid having a non-vanishing velocity with respect to the matter and radiation large-scale rest frames. We consider homogeneous anisotropic cosmological models with four fluids…

Astrophysics · Physics 2008-11-26 Jose Beltran Jimenez , Antonio L. Maroto

In this mini-review we discuss first why we should investigate cosmological models beyond LCDM. We then show how to describe dark energy or modified gravity models in a fluid language with the help of one background and two perturbation…

Cosmology and Nongalactic Astrophysics · Physics 2012-09-24 Martin Kunz

This paper is devoted to study the Bianchi type III model in the presence of anisotropic fluid in f(R) gravity. Exponential and power-law volumetric expansions are used to obtain exact solutions of the field equations. We discuss the…

General Relativity and Quantum Cosmology · Physics 2011-02-16 M. Sharif , H. Rizwana Kausar

We investigate cosmologies where the accelerated expansion of the Universe is driven by a field with an anisotropic equation of state. We model such scenarios within the Bianchi I framework, introducing two skewness parameters to quantify…

Astrophysics · Physics 2009-06-23 Tomi Koivisto , David F. Mota

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
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