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The generalized Chaplygin gas (GCG) model allows for an unified description of the recent accelerated expansion of the Universe and the evolution of energy density perturbations. This dark energy - dark matter unification is achieved…

General Relativity and Quantum Cosmology · Physics 2014-11-17 M. C. Bento , O. Bertolami , A. A. Sen

We investigate a phenomenological extension of the standard $\Lambda$CDM framework, the $\Omega_1\Omega_2$-$\Lambda$CDM model, in which the total energy density of the universe is expanded in powers of $1+z$. This parameterization recovers…

Cosmology and Nongalactic Astrophysics · Physics 2026-02-20 Suresh Kumar

A two-component fluid representing dark energy is studied. One of the components has a polytropic form, while the other has a barotropic form. Exact solutions are obtained and the cosmological parameters are constrained using supernova type…

A new kind of accelerating flat model with no dark energy that is fully dominated by cold dark matter (CDM) is investigated. The number of CDM particles is not conserved and the present accelerating stage is a consequence of the negative…

Astrophysics · Physics 2014-11-18 J. A. S. Lima , F. E. Silva , R. C. Santos

The unparticle has been suggested as a candidate of dark matter. We investigated the growth rate of the density perturbation for the unparticle dark matter in the flat Universe. First, we consider the model in which unparticle is the sole…

General Relativity and Quantum Cosmology · Physics 2009-11-05 Songbai Chen , Xiangyun Fu , Jiliang Jing

We investigate the clustering properties of dynamical dark energy using the latest cosmological observations. We describe the dark energy perturbation within two complementary frameworks, namely the Parameterized Post-Friedmann (PPF)…

Cosmology and Nongalactic Astrophysics · Physics 2025-12-02 Yuhang Yang , Qingqing Wang , Xin Ren , Emmanuel N. Saridakis , Yi-Fu Cai

We study the bulk flow of the local universe using Type Ia supernova data by considering a class of cosmological model which is spatially flat,(FRW) space-times and contains cold dark matter and $Q$ component (QCDM models) of the fluid as a…

Cosmology and Nongalactic Astrophysics · Physics 2022-05-31 A. Salehi , M. Yarahmadi , S. Fathi

The bulk viscosity of cosmological fluid and the creation of cold dark matter both result in the generation of irreversible entropy (related to dissipative processes) in a homogeneous and isotropic universe. To consider such effects, the…

Cosmology and Nongalactic Astrophysics · Physics 2014-12-16 Nobuyoshi Komatsu , Shigeo Kimura

In this paper, we have presented an FLRW universe containing two-fluids (baryonic and dark energy) with a deceleration parameter (DP) having a transition from past decelerating to the present accelerating universe. In this model, dark…

General Physics · Physics 2021-08-03 Anirudh Pradhan , G. K. Goswami , A. Beesham , Archana Dixit

Using an approximate solution to the $N$-body problem in general relativity, and the \emph{principle of local isotropy at any point}, we construct a cosmological model, with zero curvature, for a universe composed uniquely by collision-less…

General Relativity and Quantum Cosmology · Physics 2014-09-11 Miguel Portilla

We compute the Bayesian evidences for one- and two-parameter models of evolving dark energy, and compare them to the evidence for a cosmological constant, using current data from Type Ia supernova, baryon acoustic oscillations, and the…

Astrophysics · Physics 2008-11-26 Andrew R Liddle , Pia Mukherjee , David Parkinson , Yun Wang

It is well known that there are several long-standing problems implying the discordance of the $\Lambda$CDM model. Although most of the models proposed to resolve these problems assume that dark matter is pressureless, it is still possible…

Cosmology and Nongalactic Astrophysics · Physics 2024-05-31 Yan-Hong Yao , Jun-Chao Wang , Xin-He Meng

We introduce a unified model of early and late dark energy. We call it {\it quintessential early dark energy} model where early and late dark energy are explained by a single scalar field {\it i.e.}, two different energy scales are related…

Cosmology and Nongalactic Astrophysics · Physics 2025-05-19 Sk. Sohail , Sonej Alam , Shiriny Akthar , Md. Wali Hossain

Weak gravitational lensing is a powerful tool for studying both the geometry and the dynamics of the Universe. Its power spectrum contains information on the sources emitting photons and on the large--scale structures that these hotons…

Cosmology and Nongalactic Astrophysics · Physics 2010-11-02 Stefano Camera , Daniele Bertacca , Antonaldo Diaferio , Nicola Bartolo , Sabino Matarrese

We explore the theoretical viability of modeling a decaying dark matter sector through a unified scalar field approach. Using exact analytical solutions of the Friedmann constraints, we map the fluid phenomenology onto a scalar field…

Cosmology and Nongalactic Astrophysics · Physics 2026-05-04 Gilberto Aguilar-Pérez , Deryan Alvarado , Miguel Cruz , Estefany Ruíz-Ramos , Joel Saavedra

We have constructed a dark energy cosmological model in the framework of generalized Brans Dicke theory (GBD) with a self-interacting potential. The source of dark energy is considered through a unified dark fluid (UDF) characterized by a…

General Relativity and Quantum Cosmology · Physics 2024-03-21 S K Tripathy , A Sendha , S K Pradhan , Z. Naik , B. Mishra

We reconsider the dynamics of the Universe in the presence of interactions in the cosmological dark sector. A class of interacting models is introduced via a real function $f\left(r\right)$ of the ratio $r$ between the energy densities of…

Cosmology and Nongalactic Astrophysics · Physics 2019-01-09 R. von Marttens , L. Casarini , D. F. Mota , W. Zimdahl

We consider the cosmological application of a (variant of) relatively newly proposed model \cite{1609.06915} unifying inflation, dark energy, dark matter, and the Higgs mechanism. The model was originally defined using additional…

General Relativity and Quantum Cosmology · Physics 2019-06-21 Denitsa Staicova , Michail Stoilov

We apply the Union2 compilation of 557 supernova Ia data, the baryon acoustic oscillation measurement of distance, the cosmic microwave background radiation data from the seven year Wilkinson Microwave Anisotropy Probe, and the Hubble…

Cosmology and Nongalactic Astrophysics · Physics 2011-07-27 Yungui Gong , Xiao-ming Zhu , Zong-Hong Zhu

Dark energy observations may be explained within general relativity using an inhomogeneous Hubble-scale depression in the matter density and accompanying curvature, which evolves naturally out of an Einstein-de Sitter (EdS) model. We…

Cosmology and Nongalactic Astrophysics · Physics 2012-12-10 Sean February , Julien Larena , Mathew Smith , Chris Clarkson
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