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A generally anisotropic equation of state originally derived in the context of Newman-Janis rotating systems allows for vacuum energy at a specific density. In this paper we examine the possibility of using that equation of state for…

General Relativity and Quantum Cosmology · Physics 2023-09-08 Philip Beltracchi

It is argued that the initial cosmological singularity is isotropic in spatially inhomogeneous brane-world models. This implies that brane cosmology may naturally give rise to a set of initial data that provide the conditions for inflation…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Alan Coley

Field theoretical scheme of regular Big Bang in 4-dimensional physical space-time, built in the framework of gauge approach to gravitation, is discussed. Regular bouncing character of homogeneous isotropic cosmological models is ensured by…

General Relativity and Quantum Cosmology · Physics 2007-05-23 A. V. Minkevich

We suggest to generalize the dark energy equation of state (EoS) by introduction the relaxation equation for pressure which is equivalent to consideration of the inhomogeneous EoS cosmic fluid which often appears as the effective model from…

High Energy Physics - Theory · Physics 2009-09-17 Shin'ichi Nojiri , Sergei D. Odintsov

Brane Gas Cosmology (BGC) is an approach to M-theory cosmology in which the initial state of the Universe is taken to be small, dense and hot, with all fundamental degrees of freedom near thermal equilibrium. Such a starting point is in…

High Energy Physics - Theory · Physics 2009-11-07 Robert Brandenberger , Damien A. Easson , Dagny Kimberly

We investigate a brane model based on Randall-Sundrum scenarios with a generic dark energy component. The latter drives the accelerated expansion at late times of the Universe. In this scheme, extra terms are added into Einstein Field…

Cosmology and Nongalactic Astrophysics · Physics 2017-09-21 Miguel A. Garcia-Aspeitia , Juan Magaña , Alberto Hernandez-Almada , V. Motta

The accelerated expansion of the universe together with its present day isotropy has posed an interesting challenge to the numerous model theories presented over the years to describe them. In this paper, we address the above questions in…

General Relativity and Quantum Cosmology · Physics 2024-11-18 Z. Haghani , H. R. Sepangi , S. Shahidi

The absence of isotropic singularity in loop quantum cosmology can be understood in an effective classical description as the universe exhibiting a Big Bounce. We show that with scalar matter field, the big bounce is generic in the sense…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Ghanashyam Date , Golam Mortuza Hossain

Bouncing cosmologies are often proposed as alternatives to standard inflation for the explanation of the homogeneity and flatness of the universe. In such scenarios, the present cosmological expansion is preceded by a contraction phase.…

High Energy Physics - Theory · Physics 2010-04-30 V. Bozza , M. Bruni

The inflationary scenario, which states that the early universe underwent a brief but dramatic period of accelerated spatial expansion, has become the current paradigm of early universe cosmology. Although inflationary cosmology has its…

General Relativity and Quantum Cosmology · Physics 2024-06-04 Eric Ling , Annachiara Piubello

In the context of brane cosmology, a scenario where our universe is a 3+1-dimensional surface (the ``brane'') embedded in a five-dimensional spacetime (the ``bulk''), we study geometries for which the brane is anisotropic - more…

High Energy Physics - Theory · Physics 2010-02-03 A. Fabbri , D. Langlois , D. A. Steer , R. Zegers

In this paper, we investigate the exact solution of an anisotropic space-time in the context of $f(Q)$ gravity, where $f\left( Q\right) $ is the arbitrary function of the non-metricity scalar $Q$. Here, we consider a specific power-law form…

General Relativity and Quantum Cosmology · Physics 2022-12-01 M. Koussour , M. Bennai

A cosmological model with anisotropic dark energy is analyzed. The amount of deviation from isotropy of the equation of state of dark energy, the skewness \delta, generates an anisotropization of the large-scale geometry of the Universe,…

Cosmology and Nongalactic Astrophysics · Physics 2011-06-28 L. Campanelli , P. Cea , G. L. Fogli , L. Tedesco

The stability of the Bianchi type I anisotropic brane cosmology is analyzed in this paper. We also study the effect of the brane solution by comparing the models on the 3-brane and the models in the conventional Einstein's space. Analysis…

High Energy Physics - Theory · Physics 2007-05-23 Chiang-Mei Chen , W. F. Kao

Homogeneous cosmology in the braneworld can be studied without solving bulk equations of motion explicitly. The reason is simply because the symmetry of the spacetime restricts possible corrections in the 4-dimensional effective equations…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Jiro Soda , Sugumi Kanno

Ekpyrotic and cyclic cosmologies provide theories of the very early and of the very late universe. In these models, the big bang is described as a collision of branes - and thus the big bang is not the beginning of time. Before the big…

Astrophysics · Physics 2011-03-10 Jean-Luc Lehners

We construct general anisotropic cosmological scenarios governed by an $f(R)=R^n$ gravitational sector. Focusing then on some specific geometries, and modelling the matter content as a perfect fluid, we perform a phase-space analysis. We…

General Relativity and Quantum Cosmology · Physics 2014-03-11 Genly Leon

Despite having a reasonably successful account of accelerated cosmology, understanding the early evolution of Universe has always been difficult for mankind. Our promising strategy is based on a novel class of symmetric teleparallel…

General Relativity and Quantum Cosmology · Physics 2022-09-12 L. Anjana Devi , S. Surendra Singh , Leishingam Kumrah , Md Khurshid Alam

If the dark energy equation of state is anisotropic, the expansion rate of the universe becomes direction-dependent at late times. We show that such models are not only cosmologically viable but that they could explain some of the observed…

Astrophysics · Physics 2010-11-11 Tomi Koivisto , David F. Mota

We study the cosmological evolution of isotropic matter on an infinitely thin conical codimension-two brane-world. Our analysis is based on the boundary dynamics of a six-dimensional model in the presence of an induced gravity term on the…

High Energy Physics - Theory · Physics 2009-11-11 Eleftherios Papantonopoulos , Antonios Papazoglou