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In this paper we consider a cosmological model whose main components are a scalar field and a generalized Chaplygin gas. We obtain an exact solution for a flat arbitrary potential. This solution have the right dust limit when the Chaplygin…

Cosmology and Nongalactic Astrophysics · Physics 2013-10-31 Sergio del Campo , Carlos R. Fadragas , Ramon Herrera , Carlos Leiva , Genly Leon , Joel Saavedra

We discuss a spatially homogeneous and anisotropic Bianchi type-I space-time with two fluids as the content of the Universe: matter and holographic dark energy in the framework of general relativity. To get the exact solutions of Einstein's…

General Relativity and Quantum Cosmology · Physics 2023-02-03 M. Koussour , M. Bennai

In this paper we investigate asymptotic isotropization. We derive the asymptotic dynamics of spatially inhomogeneous cosmological models with a perfect fluid matter source and a positive cosmological constant near the de Sitter equilibrium…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Woei Chet Lim , Henk van Elst , Claes Uggla , John Wainwright

We review various cosmological models with a local underdense region (local void) and the averaged models with the backreaction of inhomogeneities, which have been proposed to explain (without assuming a positive cosmological constant) the…

Cosmology and Nongalactic Astrophysics · Physics 2009-06-09 Kenji Tomita

We present a simple generalisation of the $\Lambda$CDM model which on the one hand reaches very good agreement with the present day experimental data and provides an internal inflationary mechanism on the other hand. It is based on Palatini…

General Relativity and Quantum Cosmology · Physics 2016-01-29 Andrzej Borowiec , Aleksander Stachowski , Marek Szydlowski , Aneta Wojnar

We present a detailed discussion of the inflationary scenario in the context of inhomogeneous cosmologies. After a review of the fundamental features characterizing the inflationary model, as referred to a homogeneous and isotropic…

General Relativity and Quantum Cosmology · Physics 2010-11-11 Giovanni Imponente , Giovanni Montani

We analyze two different algorithms for constructing weakly inhomogeneous models for the low-redshift Universe, in order to provide a tool for testing the geodesic dynamics, within the sphere of validity for the Universe acceleration. We…

General Relativity and Quantum Cosmology · Physics 2020-07-14 P. Marcoccia , G. Montani

In `entropic cosmology', instead of a cosmological constant $\Lambda$, an extra driving term is added to the Friedmann equation and the acceleration equation, taking into account the entropy and the temperature on the horizon of the…

Cosmology and Nongalactic Astrophysics · Physics 2013-03-14 Nobuyoshi Komatsu , Shigeo Kimura

Starting from an inhomogeneous space-time model of the universe we could recreate a scenario of recent time accelerating universe dominated by Dark Energy type of fluid. The background matter component of such a universe was considered to…

General Relativity and Quantum Cosmology · Physics 2023-02-06 Subhra Bhattacharya

If expanding and contracting regions coexist in the universe, the speed of the cosmic volume expansion can be accelerated. We construct simple inhomogeneous dust-filled universe models in which the speed of the cosmic volume expansion is…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Tomohiro Kai , Hiroshi Kozaki , Ken-ichi nakao , Yasusada Nambu , Chul-Moon Yoo

An overview of some recent developments in inhomogeneous models is presented. As the volume and precision of cosmological data improves, it will become more and more essential to understand the non-linear behaviour of the Einstein field…

General Relativity and Quantum Cosmology · Physics 2010-01-06 Charles Hellaby

We investigate a cosmological model based on a massless nonlinear spinor field coupled to a Modified Chaplygin Gas (MCG) in the Kantowski--Sachs spacetime, aiming to probe anisotropies and unified dark sector dynamics. The model parameters…

General Relativity and Quantum Cosmology · Physics 2026-05-07 Mahendra Goray , Bijan Saha

We investigate the dynamical properties of a class of spatially homogeneous and isotropic cosmological models containing a barotropic perfect fluid and multiple scalar fields with independent exponential potentials. We show that the…

General Relativity and Quantum Cosmology · Physics 2009-10-31 A. A. Coley , R. J. van den Hoogen

The present work aims to investigate an interacting Umami Chaplygin gas in the background dynamics of a spatially flat Friedmann-Lemaitre-Robertson-Walker (FLRW) universe when adiabatic particle creation is allowed. Here, the universe is…

General Relativity and Quantum Cosmology · Physics 2024-12-30 Goutam Mandal , Sujay Kr. Biswas

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 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

Using the exact Lemaitre-Bondi-Tolman solution with a non-vanishing cosmological constant $\Lambda$, we investigate how the presence of a local spherically-symmetric inhomogeneity can affect apparent cosmological observables, such as the…

Cosmology and Nongalactic Astrophysics · Physics 2015-09-01 Antonio Enea Romano , Misao Sasaki , Alexei A. Starobinsky

We describe the universe as a local, inhomogeneous spherical bubble embedded in a flat matter dominated FLRW universe. Generalized exact Friedmann equations describe the expansion of the universe and an early universe inflationary de Sitter…

Astrophysics · Physics 2007-05-23 J. W. Moffat

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

In this study, we investigated the effects of incorporating barotropic fluids on cosmological solutions within the general relativity (GR) framework. We proposed a modified version of the barotropic fluid with the EoS, $p=\zeta _0 \rho…

General Relativity and Quantum Cosmology · Physics 2025-04-29 Rajdeep Mazumdar , Mrinnoy M. Gohain , Kalyan Bhuyan