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The growth of large scale structure is studied in a universe containing both cold dark matter (CDM) and generalized Chaplygin gas (GCg). GCg is assumed to contribute only to the background evolution of the universe while the CDM component…

Astrophysics · Physics 2009-11-10 T. Multamaki , M. Manera , E. Gaztanaga

The universe media is considered as a non-perfect fluid with bulk viscosity and described by a more general equation of state. We assume the bulk viscosity is a linear combination of the two terms: one is constant, and the other is…

Astrophysics · Physics 2009-03-19 Xin-He Meng , Jie Ren , Ming-Guang Hu

If the equation of state for "dark energy" varies periodically, the expansion of the Universe may have undergone alternating eras of acceleration and deceleration. We examine a specific form that survives existing observational tests, does…

Astrophysics · Physics 2008-11-26 Gabriela Barenboim , Olga Mena , Chris Quigg

Cosmological fluids with a Generalized Equation of State (GEoS) are here considered, whose corresponding EoS parameter $\omega$ describes a fluid with phantom behavior, namely $\omega<-1$, but leading to universes free of singularities at…

General Relativity and Quantum Cosmology · Physics 2018-12-26 Felipe Contreras , Norman Cruz , Emilio Elizalde , Esteban González , Sergei Odintsov

We assume that dark matter and dark energy satisfy the unified equation of state: $p=B(z)\rho$, with $p=p_{dE}$, $\rho=\rho_{dm}+\rho_{dE}$, where the pressure of dark matter $p_{dm}=0$ has been taken into account. A special function…

Astrophysics · Physics 2009-11-10 Wei Wang , Yuan-xing Gui , Suhong Zhang , Guanghai Guo , Ying Shao

We have explored cold dark matter and holographic dark energy cosmological models with big rip singularity. To obtain the solution of the field equation, we have supposed that scalar expansion $\theta$ is proportional to shear scalar…

General Relativity and Quantum Cosmology · Physics 2023-03-13 D. D. Pawar , S. D. Patil , V. J. Dagwal

Cosmological observations strongly suggest the presence of dark energy which comprises the majority of the current energy density of the universe. The equation of state relating the pressure and energy density of this dark energy, p = w…

Astrophysics · Physics 2007-05-23 Eric Gawiser

The modified Chaplygin gas (MCG) is a strong candidate for the unified model of dark matter and dark energy. The equation of state of this modified model is valid from the radiation era to the $\Lambda$CDM model. In early epoch (when $\rho$…

General Relativity and Quantum Cosmology · Physics 2009-05-12 Subenoy Chakraborty , Tanwi Bandyopadhyay

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 Tolman-Bondi-Lema\^itre type of inhomogeneous spacetime with generalised Chaplygin gas equation of state given by $p = -\frac{A}{\rho^{\alpha}}$ is investigated where $ \alpha$ is a constant. We get an inhomogeneous spacetime at early…

General Relativity and Quantum Cosmology · Physics 2019-11-07 D. Panigrahi , S. Chatterjee

This paper deals with a cosmological model in which the universe is filled with tachyon dark energy in order to describe current and future accelerating expansion. We obtain that the simplest condition for the regime of phantom energy to…

Astrophysics · Physics 2009-11-10 Pedro F. Gonzalez-Diaz

The effects which quantum fields and an $\alpha_0 R^2$ term in the gravitational Lagrangian have on future singularities are investigated. While all values of $\alpha_0$ are considered, an emphasis is placed on those values which are…

General Relativity and Quantum Cosmology · Physics 2017-08-24 Eric D. Carlson , Paul R. Anderson , John R. Einhorn , Bradley Hicks , Andrew J. Lundeen

We review the essential features of the Chaplygin gas cosmological models and provide some examples of appearance of the Chaplygin gas equation of state in modern physics. A possible theoretical basis for the Chaplygin gas in cosmology is…

General Relativity and Quantum Cosmology · Physics 2016-11-09 V. Gorini , A. Kamenshchik , U. Moschella , V. Pasquier

By studying the present cosmological data, particularly on CMB, SNeIA and LSS, we find that the future fate of the universe, for simple linear models of the dark energy equation-of-state, can vary between the extremes of (I) a divergence of…

Astrophysics · Physics 2009-11-10 Paul H. Frampton

In this work we explore an alternative phenomenological model to Chaplygin gas proposed by H. Hova et. al., consisting on a modification of a perfect fluid, to explain the dynamics of dark matter and dark energy at cosmological scales…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-30 A. Hernandez-Almada , Juan Magana , Miguel A. Garcia-Aspeitia , V. Motta

Interest on the possible future scenarios the universe could have has grew substantially with breakthroughs on late-time acceleration. Holographic dark energy (HDE) presents a very interesting approach towards addressing late-time…

General Relativity and Quantum Cosmology · Physics 2026-03-19 I. Brevik , Maxim Khlopov , S. D. Odintsov , Alexander V. Timoshkin , Oem Trivedi

The properties of future singularities are investigated in the universe dominated by dark energy including the phantom-type fluid. We classify the finite-time singularities into four classes and explicitly present the models which give rise…

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

We consider the fate of future singularities in the effective dynamics of loop quantum cosmology. Non-perturbative quantum geometric effects which lead to $\rho^2$ modification of the Friedmann equation at high energies result in generic…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. Sami , Parampreet Singh , Shinji Tsujikawa

It is shown that in the cosmological models based on a vacuum energy decaying as a^{-2}, where a is the scale factor of the universe, the fate of the universe in regard to whether it will collapse in future or expand forever is determined…

Astrophysics · Physics 2009-10-31 Murat Özer

The recently introduced relativistic Lagrangian darkon fluid model (EPJ C (2015) 75:9) is generalized to a self-gravitating, irrotational, pressure-less and stress free geodesic fluid, whose energy-momentum tensor is dust-like with…

General Physics · Physics 2016-04-18 Peter C. Stichel
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