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Unification of dark matter and dark energy as short- and long-range manifestations of a single cosmological substance is possible in models described by the generalized Chaplygin gas equation of state. We show it admits halo-like structures…

General Relativity and Quantum Cosmology · Physics 2017-12-20 T. de Beer , J. W. van Holten

Within our recent thermodynamic model of gravity the dark energy is identified with the energy of collective gravitational interactions of all particles in the universe, which is missing in the standard treatments. For a simple model…

General Physics · Physics 2014-04-24 Merab Gogberashvili , Igor Kanatchikov

We consider FLRW cosmological models with standard Friedmann equations, but leaving free the equation of state. We assume that the dark energy content of the universe is encoded in an equation of state $p=f(\rho)$, which is expressed with…

General Relativity and Quantum Cosmology · Physics 2014-11-20 L. Fernandez-Jambrina , R. Lazkoz

This paper is devoted to the investigation of modified Chaplygin gas model in the context of solvable k-essence cosmologies. For this purpose, we construct equations of state parameter of this model for some particular values of the…

General Physics · Physics 2012-07-31 M. Sharif , K. R. Yesmakhanova , S. Rani , R. Myrzakulov

We use the framework of a recently proposed model of reduced relativistic gas (RRG) to obtain the bounds for $\Omega$'s of Dark Matter and Dark Energy (in the present case, a cosmological constant), taking into consideration an arbitrary…

Cosmology and Nongalactic Astrophysics · Physics 2013-05-30 Julio C. Fabris , Ilya L. Shapiro , A. M. Velasquez-Toribio

Based on the proposed earlier by the Author approach to macroscopic description of scalar interaction, this paper develops the macroscopic model of relativistic plasma with a fantom scalar interaction of elementary particles. In the article…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Yu. G. Ignatyev , A. A. Agathonov , D. Yu. Ignatyev

The theoretical and observational consequences of thermodynamics of open systems, which allow particle creation are investigated in modified $f(R,T)$ ($R$ is the Ricci scalar and $T$ is the trace of energy-momentum tensor) theory of gravity…

General Relativity and Quantum Cosmology · Physics 2014-08-26 C. P. Singh , Vijay Singh

We study how a strong gravity affects the equation of state of matters. For this purpose, we employ a canonical ensemble of classical monoatomic ideal gas inside a box in a Rindler spacetime. The total energy decreases monotonically with…

General Relativity and Quantum Cosmology · Physics 2017-05-03 Hyeong-Chan Kim , Chueng-Ryong Ji

A classical (non-quantum-mechanical) relativistic ideal gas in thermodynamic equilibrium in a uniformly accelerated frame of reference is studied using Gibbs's microcanonical and grand canonical formulations of statistical mechanics. Using…

Classical Physics · Physics 2015-05-20 Domingo J. Louis-Martinez

Specific internal self-interactions in gaseous cosmic fluids are shown to give rise to effective negative pressures which may violate the strong energy condition. On this basis we discuss the transition from an initial de Sitter phase to a…

Astrophysics · Physics 2016-08-16 W. Zimdahl , A. B. Balakin , D. J. Schwarz , D. Pavón

A general framework for an emergent universe scenario has been given which makes use of an equation of state. The general features of the model have also been studied and possible primordial composition of the universe have been suggested.

General Relativity and Quantum Cosmology · Physics 2009-11-11 S. Mukherjee , B. C. Paul , N. K. Dadhich , S. D. Maharaj , A. Beesham

We generalize the cosmic energy equation to the case when massive particles interact via a modified gravitational potential of the form phi(a, r), which is allowed to explicitly depend upon the cosmological time through the expansion factor…

Cosmology and Nongalactic Astrophysics · Physics 2010-12-23 Yuri Shtanov , Varun Sahni

On the basis of the relativistic kinetic theory the relativistic statistical systems with scalar interaction particles are investigated. The self-consistent system of the equations describing self-gravitating plasma with interpartial scalar…

General Relativity and Quantum Cosmology · Physics 2013-07-10 Yu. G. Ignat'ev

We consider the cosmological system with two interacting fluids: dark energy and dark matter, in a homogeneous and isotropic universe with dissipation. The modified gravitational equation for dark matter is solved. The analytic…

General Relativity and Quantum Cosmology · Physics 2015-08-19 I. Brevik , V. V. Obukhov , A. V. Timoshkin

General relativity marked the beginning of modern cosmology and it has since been at the centre of many of the key developments in this field. In the present review, we discuss the general-relativistic dynamics and perturbations of the…

Astrophysics · Physics 2009-06-23 Christos G. Tsagas , Anthony Challinor , Roy Maartens

The basic concepts of a generalized relativistic density functional approach to the equation of state of dense matter are presented. The model is an extension of relativistic mean-field models with density-dependent couplings. It includes…

Nuclear Theory · Physics 2015-04-08 Stefan Typel

Several approaches to the matter creation problem in the context of cosmological models are summarily reviewed. A covariant formulation of the general relativistic imperfect simple fluid endowed with a process of matter creation is…

Astrophysics · Physics 2007-08-28 J. A. S. Lima , M. O. Calvao , I. Waga

We suggest a limit of Einstein equations incorporating the state $g_{\mu\nu}=0$ as a solution. The large scale behavior of this theory has interesting properties. For a spherical source, the velocity profile for circular motions is of the…

High Energy Physics - Theory · Physics 2008-11-26 Maximo Banados

We construct a cosmological model which is physically reasonable, mathematically tractable, and extends the study of CDM models to the case where the equations of state (EoS) for matter and dark energy (DE) vary with time. It is based on…

General Relativity and Quantum Cosmology · Physics 2012-06-14 J. Ponce de Leon

It was shown, that the presence of the so-called X-matter with an equation of state, which lies between limits of the strong and weak energy conditions, allows the variety of the cosmological scenarios in the relativistic theory of gravity.…

General Relativity and Quantum Cosmology · Physics 2007-05-23 V. L. Kalashnikov