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We discuss the Buchert equations, which describe the average expansion of an inhomogeneous dust universe. In the limit of small perturbations, they reduce to the Friedmann-Robertson-Walker equations. However, when the universe is very…

Astrophysics · Physics 2008-11-26 Syksy Rasanen

Cosmic acceleration may be the result of unknown physical processes involving either new fields in high energy physics or modifications of gravitation theory. In the latter case, such modifications are usually related to the existence of…

Astrophysics · Physics 2009-11-10 J. S. Alcaniz , N. Pires

In this letter, I have proposed a model of variable modified Chaplygin gas and shown its role in accelerating phase of the universe. I have shown that the equation of state of this model is valid from the radiation era to quiessence model.…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Ujjal Debnath

In this work we have studied the possibility of obtaining cosmic acceleration in Brans-Dicke theory with varying or constant $\omega$ (Brans- Dicke parameter) and with or without self-interacting potential, the background fluid being…

General Relativity and Quantum Cosmology · Physics 2009-11-13 Writambhara Chakraborty , Ujjal Debnath

The mass power spectrum for a Universe dominated by the Chaplygin gas is evaluated numerically from scales of the order of the Hubble horizon to 100 Mpc. The results are compared with a pure baryonic Universe and a cosmological constant…

Astrophysics · Physics 2016-08-16 J. C. Fabris , S. V. B. Gonçalves , P. E. de Souza

In this work we set observational constraints of the Superfluid Chaplygin gas model, which gives a unified description of the dark sector of the Universe as a Bose-Einstein condensate (BEC) that behaves as dark energy (DE) while it is in…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-12 Ruth Lazkoz , Ariadna Montiel , Vincenzo Salzano

This paper explores the possibility of treating the exotic Chaplygin-gas (CG) fluid model as some manifestation of an $f(T)$ gravitation. To this end, we use the different cosmological CG equations of state, compare them with the equation…

General Relativity and Quantum Cosmology · Physics 2019-10-02 Shambel Sahlu , Joseph Ntahompagaze , Maye Elmardi , Amare Abebe

We provide an explicit calculation of the evolution of the cosmic entanglement entropy in the early universe before the matter dominant era. This is made possible by invoking the generalized Chaplygin gas (GCG) model, which has the…

General Relativity and Quantum Cosmology · Physics 2011-12-08 Pisin Chen , Yuezhen Niu

The Chaplygin gas has been proposed as a possible dark energy, dark matter candidate. As a working fluid in a Friedmann-Robertson-Walker universe, it exhibits early behavior reminiscent of dark matter, but at later times is more akin to a…

General Relativity and Quantum Cosmology · Physics 2011-03-07 T. C. Lipscombe

The generalized Chaplygin gas (GCG) model in spatially flat universe is investigated. The cosmological consequences led by GCG model including the evolution of EoS parameter, deceleration parameter and dimensionless Hubble parameter are…

General Relativity and Quantum Cosmology · Physics 2011-06-10 M. Malekjani , A. Khodam-Mohammadi , N. Nazari-Pooya

The cosmological dynamics of a brane world scenario where the bulk action is taken as a generic function of the Ricci scalar is considered in a framework where the use of the $\mathbb{Z}_2$ symmetry and Israel junction conditions are…

General Relativity and Quantum Cosmology · Physics 2013-08-13 Zahra Haghani , Hamid Reza Sepangi , Shahab Shahidi

Recent observations from type Ia Supernovae and from cosmic microwave background (CMB) anisotropies have revealed that most of the matter of the Universe interacts in a repulsive manner, composing the so-called dark energy constituent of…

General Relativity and Quantum Cosmology · Physics 2009-11-11 M. S. Santos , S. V. B. Gonçalves , J. C. Fabris , E. M. de Gouveia Dal Pino

We derive the constraints set by several experiments on the quartessence Chaplygin model (QCM). In this scenario, a single fluid component drives the Universe from a nonrelativistic matter-dominated phase to an accelerated expansion phase…

Astrophysics · Physics 2009-11-10 Martin Makler , Sergio Quinet de Oliveira , Ioav Waga

A model of an emergent universe is obtained in brane world. Here the bulk energy is in the form of cosmological constant, while the brane consists of the Chaplygin gas with the modified equation of state such as $p=A\rho-B/\rho$. Initially…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Asit Banerjee , Tanwi Bandyopadhyay , Subenoy Chakraborty

A Universe containing uniform magnetic fields, strings, or domain walls is shown to have an ellipsoidal expansion. This case has motivations from observational cosmology especially the anomaly concerning the low quadrupole amplitude…

General Relativity and Quantum Cosmology · Physics 2020-06-25 Mohamed Lamine Abdelali , Noureddine Mebarki

In this paper, we study cosmologies containing the reduced modified Chaplygin gas (RMCG) fluid which is reduced from the modified Chaplygin gas $p=A\rho-B\rho^{-\alpha}$ for the value of $\alpha=-1/2$. In this special case, dark…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-18 Jianbo Lu , Danhua Geng , Lixin Xu , Yabo Wu , Molin Liu

The purpose of this paper is to examine the possible existence or construction of traversable wormholes supported by generalized Chaplygin gas (GCG) by starting with a general line element and the Einstein tensor, together with the equation…

General Relativity and Quantum Cosmology · Physics 2009-03-16 Peter K. F. Kuhfittig

In the framework of spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) space-time, we investigate a two-fluid cosmological model where a tachyon scalar field with self-interacting potential and a modified chaplygin gas with…

General Relativity and Quantum Cosmology · Physics 2024-12-25 Goutam Mandal , Sujay Kr. Biswas

We present some exact solutions of the Einstein equations with an anisotropic fluid exploiting the Chaplygin equation of state. The solutions describe spacetimes with two identical T regions and an intermediate static spherically symmetric…

General Relativity and Quantum Cosmology · Physics 2013-04-23 Anna Mokeeva , Vladimir Popov

Recently it was found that dark energy in the form of phantom generalized Chaplygin gas may lead to a new form of the cosmic doomsday, the big freeze singularity. Like the big rip singularity, the big freeze singularity would also take…

Astrophysics · Physics 2009-11-13 Artyom V. Yurov , Artyom V. Astashenok , Pedro F. Gonzalez-Diaz
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