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Spherically symmetric dark energy structures are investigated in the framework of a generalized Chaplygin gas (GCG), which has an equation of state of the form $P = - A/\rho^{\alpha}} $. We also study these in a modified GCG equation of…

General Relativity and Quantum Cosmology · Physics 2007-06-07 Abiy G. Tekola

The supernova type Ia observational data are fitted using a model with cold dark matter and the Chaplygin gas. The Chaplygin gas, which is characterized by a negative pressure varying with the inverse of density, represents in this model…

Astrophysics · Physics 2007-05-23 J. C. Fabris , S. V. B. Goncalves , P. E. de Souza

Recently Tsallis cosmology has been presented as a novel proposal for alleviating both $H_0$ and $\sigma_8$ tensions. Hence a universe filled with matter and radiation as perfect fluids and considering the Tsallis entropy is confronted…

Cosmology and Nongalactic Astrophysics · Physics 2024-07-23 M. L. Mendoza-Martínez , A. Cervantes-Contreras , J. J. Trejo-Alonso , A. Hernandez-Almada

The Chaplygin gas model, characterized by an equation of state of the type $p = - \frac{A}{\rho}$ emerges naturally from the Nambu-Goto action of string theory. This fluid representation can be recast under the form of a tachyonic field…

General Relativity and Quantum Cosmology · Physics 2015-05-13 C. E. M. Batista , J. C. Fabris , M. Morita

We suggest a perturbative approach for generic choices for the universe equation of state and introduce a novel framework for studying mass varying neutrinos (MaVaN's) coupled to the dark sector. For concreteness, we examine the coupling…

Astrophysics · Physics 2010-01-16 Alex E. Bernardini , O. Bertolami

Cosmologies with a Chaplygin gas have recently been explored with the objective of explaining the transition from a dust dominated epoch towards an accelerating expansion stage. We consider the hypothesis that the transition to the…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Mariam Bouhmadi-Lopez , Paulo Vargas Moniz

The hypothesis that dark matter and dark energy are unified through the Chaplygin gas is reexamined. Using generalizations of the spherical model which incorporate effects of the acoustic horizon we show that an initially perturbative…

Astrophysics · Physics 2008-11-26 Neven Bilic , Robert J. Lindebaum , Gary B. Tupper , Raoul D. Viollier

We explore a generalised unified dark energy model that incorporates a non-minimal interaction between a tachyonic fluid and an additional scalar field. Specifically, we require that the second field possesses a vacuum energy, introducing…

General Relativity and Quantum Cosmology · Physics 2023-08-31 Peter K. S. Dunsby , Orlando Luongo , Marco Muccino

Warm inflationary universe models in the context of a Chaplygin gas equation are studied. General conditions required for these models to be realizable are derived and discussed. By using a chaotic potential we develop models for a…

Astrophysics · Physics 2008-12-18 Sergio del Campo , Ramon Herrera

We show that the observed rotation curves of spiral galaxies constrain the sound speed of the dark matter to be $c_s < 10^{-4} c$, where $c$ is the speed of light in vacuum. Using the Modified Chaplygin Gas as a representative example of a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-06 P. P. Avelino , V. M. C. Ferreira

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

This study examines accelerated cosmic expansion using the Viscous Modified Chaplygin Gas (VMMG) and Generalized Cosmic Chaplygin Gas (GCCM) within Horava-Lifshitz gravity. Our aim is to constrain essential cosmological parameters, such as…

Cosmology and Nongalactic Astrophysics · Physics 2024-08-12 Sayani Maity , Himanshu Chaudhary , Ujjal Debnath , S. K. Maurya , G. Mustafa

In this letter, we have considered a model of the universe filled with modified Chaplygin gas and another fluid (with barotropic equation of state) and its role in accelerating phase of the universe. We have assumed that the mixture of…

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

We study the late-time evolution of the Universe where dark energy (DE) is parametrized by a modified generalized Chaplygin gas (mGCG) on top of cold dark matter (CDM). We also take into account the radiation content of the Universe. In…

General Relativity and Quantum Cosmology · Physics 2015-12-22 Mariam Bouhmadi-López , Maxim Brilenkov , Ruslan Brilenkov , João Morais , Alexander Zhuk

In this work we study to which extent the knowledge of spatial topology may place constraints on the parameters of the generalized Chaplygin gas (GCG) model for unification of dark energy and dark matter. By using both the Poincar\'e…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. C. Bento , O. Bertolami , M. J. Rebouças , P. T. Silva

We consider a double polytropic cosmological fluid and demonstrate that, when one constituent resembles a bare cosmological constant while the other emulates a generalized Chaplygin gas, a good description of the Universe's large-scale…

General Relativity and Quantum Cosmology · Physics 2024-03-27 Peter K. S. Dunsby , Orlando Luongo , Marco Muccino , Vineshree Pillay

We consider the scenario emerging from the dynamics of a generalized $d$-brane in a $(d+1, 1)$ spacetime. The equation of state describing this system is given in terms of the energy density, $\rho$, and pressure, $p$, by the relationship…

General Relativity and Quantum Cosmology · Physics 2009-11-07 M. C. Bento , O. Bertolami , A. A. Sen

In this paper we study the interaction between the general form of viscous varying modified cosmic Chaplygin gas and the Tachyon fluid in the framework of Einstein gravity. We want to reconstruct the Tachyon potential and total equation of…

General Relativity and Quantum Cosmology · Physics 2013-08-05 Jafar Sadeghi , Hoda Farahani

A flat FLRW cosmological model with perfect fluid comprising of variable Chaplygin gas has been studied in context of f(R; T) gravity with particle creation. The considered scale factors describe the accelerated expansion of universe due to…

General Relativity and Quantum Cosmology · Physics 2020-02-12 N. Hulke , G. P. Singh , Binaya K. Bishi , A. Singh

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