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Any unified dark matter cosmology can be decomposed into dark matter interacting with vacuum energy, without introducing any additional degrees of freedom. We present observational constraints on an interacting vacuum plus dark energy…

Cosmology and Nongalactic Astrophysics · Physics 2013-04-16 Yuting Wang , David Wands , Lixin Xu , Josue De-Santiago , Alireza Hojjati

In cosmology many dramatically different scenarios with the past (big bang versus bounce) and in the future (de Sitter versus big rip) singularities are compatible with the present day observations. This difficulty is called the degeneracy…

Astrophysics · Physics 2009-11-13 Wlodzimierz Godlowski Marek Szydlowski

We have assumed FRW model of the universe in Einstein-Aether gravity filled with dark matter and Modified Chaplygin gas (MCG) type dark energy. We present the Hubble parameter in terms of some unknown parameters and observational parameters…

General Relativity and Quantum Cosmology · Physics 2013-10-09 Ujjal Debnath

The equation of state of Chaplygin Gas is one of the simplest ways to illustrate dark energy effects during the late time. Indeed, while one uses the equation of state of Chaplygin Gas, the continuity equation gives specific energy density…

General Physics · Physics 2018-07-20 H. R. Fazlollahi

Both scalar fields and (generalized) Chaplygin gases have been widely used separately to characterize the dark sector of the Universe. Here we investigate the cosmological background dynamics for a mixture of both these components and…

Cosmology and Nongalactic Astrophysics · Physics 2017-08-02 S. del Campo , J. C. Fabris , R. Herrera , W. Zimdahl

We study the clustering Generalized Chaplygin Gas (GCG) as a possible candidate for dark matter-dark energy unification. The vanishing speed of sound ($c_{s}^2 = 0$) for the GCG fluid can be obtained by incorporating higher derivative…

Cosmology and Nongalactic Astrophysics · Physics 2014-10-22 Sumit Kumar , Anjan A. Sen

We consider an anisotropic brane-world model with Bianchi type I and V geometry, without mirror symmetry or any form of junction conditions. The generalized Chaplygin gas, which interpolates between a high density relativistic era and a…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Malihe Heydari-Fard , Hamid R. Sepangi

In this paper, we propose a new unified dark fluid (UDF) model with equation of state (EoS) $w(a)=-\alpha/(\beta a^{-n}+1)$, which includes the generalized Chaplygin gas model (gGg) as its special case, where $\alpha$, $\beta$ and $n$ are…

Cosmology and Nongalactic Astrophysics · Physics 2012-10-22 Lixin Xu

Type Ia supernovae (SNIe) are generally accepted to act as standardisable candles, and their use in cosmology led to the first confirmation of the as yet unexplained accelerated cosmic expansion. Many of the theoretical models to explain…

Cosmology and Nongalactic Astrophysics · Physics 2018-10-31 Bill S. Wright , Baojiu Li

We explicitly demonstrate that, contrary to recent claims, the dynamics of a generalized Chaplygin gas model with an equation of state $p=-C$ (where $C$ is a positive constant) is equivalent to that of a standard $\Lambda$CDM model to first…

Astrophysics · Physics 2009-11-10 P. P. Avelino , L. M. G. Beca , J. P. M. de Carvalho , C. J. A. P. Martins

We consider a universe filled by a modified generalized Chaplygin gas together with a pressureless dark matter component. We get a thermodynamical interpretation for the modified generalized Chaplygin gas confined to the apparent horizon of…

General Relativity and Quantum Cosmology · Physics 2016-05-18 H. Ebadi , H. Moradpour

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

Recently H(z) data obtained from differential ages of galaxies have been proposed as a new geometrical probe of dark energy. In this paper we use those data, combined with other background tests (CMB shift and SNIa data), to constrain a set…

Astrophysics · Physics 2009-11-13 Ruth Lazkoz , Elisabetta Majerotto

Observational manifestations of accelerated expansion of the universe, in particular, recent data for Type Ia supernovae, baryon acoustic oscillations, for the Hubble parameter $H(z)$ and cosmic microwave background constraints are…

General Relativity and Quantum Cosmology · Physics 2016-08-02 G. S. Sharov

Gamma-ray bursts (GRBs) being the most luminous among known cosmic objects carry an essential potential for cosmological studies if properly used as standard candles. In this paper we test with GRBs the cosmological predictions of the…

We have considered the FRW universe in loop quantum cosmology (LQC) model filled with the dark matter (perfect fluid with negligible pressure) and the modified Chaplygin gas (MCG) type dark energy. We present the Hubble parameter in terms…

General Physics · Physics 2015-06-05 Shuvendu Chakraborty , Ujjal Debnath , Chayan Ranjit

The $\Lambda$ cold dark matter ($\Lambda\textrm{CDM}$) model is currently known as the simplest cosmology model that best describes observations with minimal number of parameters. Here we introduce a cosmology model that is preferred over…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-05 Chan-Gyung Park

The $\Lambda$CDM framework offers a remarkably good description of our universe with a very small number of free parameters, which can be determined with high accuracy from currently available data. However, this does not mean that the…

Cosmology and Nongalactic Astrophysics · Physics 2015-07-22 Yves Zolnierowski , Alain Blanchard

The cosmic coincidence problem is a serious challenge to dark energy model. We suggest a quantitative criteria for judging the severity of the coincidence problem. Applying this criteria to three different interacting models, including the…

Cosmology and Nongalactic Astrophysics · Physics 2009-07-24 Hongsheng Zhang , Heng Yu , Zong-Hong Zhu , Yungui Gong

We study cosmological models with modified Chaplygin gas (in short, MCG) to determine observational constraints on its EoS parameters. The observational data of the background and the growth tests are employed. The background test data…

Cosmology and Nongalactic Astrophysics · Physics 2015-04-02 Bikash Chandra Paul , Prasenjit Thakur , Aroonkumar Beesham