Scalar perturbations in the late Universe: viability of the Chaplygin gas models
Abstract
We study the latetime evolution of the Universe where dark energy (DE) is parametrised by a modified generalised Chaplygin gas (mGCG) on top of cold dark matter (CDM) . We also take into account the radiation content of the Universe. In this context, the late stage of the evolution of the universe refers to the epoch where CDM is already clustered into inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies). Under these conditions, the mechanical approach is an adequate tool to study the Universe deep inside the cell of uniformity. To be more accurate, we study scalar perturbations of the FriedmannLemaȋtreRobertsonWalker metric due to inhomogeneities of CDM as well as fluctuations of radiation and mGCG, the later driving the latetime acceleration of the universe. Our analysis applies as well to the case where mGCG plays the role of DM and DE . We select the sets of parameters of the mGCG that are compatible with the mechanical approach. These sets define prospective mGCG models. By comparing the selected sets of models with some of the latest observational data results, we conclude that the mGCG is in tight agreement with those observations particularly for a mGCG playing the rolemore »
 Authors:
 Departamento de Física, Universidade da Beira Interior, 6200 Covilhã (Portugal)
 Department of Theoretical Physics, Odessa National University, Dvoryanskaya st. 2, Odessa 65082 (Ukraine)
 Department of Theoretical Physics, University of the Basque Country UPV/EHU, P.O. Box 644, 48080 Bilbao (Spain)
 Astronomical Observatory, Odessa National University, Dvoryanskaya st. 2, Odessa 65082 (Ukraine)
 Publication Date:
 OSTI Identifier:
 22525119
 Resource Type:
 Journal Article
 Resource Relation:
 Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2015; Journal Issue: 12; Other Information: Country of input: International Atomic Energy Agency (IAEA)
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; COMPARATIVE EVALUATIONS; COSMIC GASES; DISTURBANCES; EVOLUTION; FLUCTUATIONS; GALAXIES; GALAXY CLUSTERS; METRICS; NONLUMINOUS MATTER; SCALARS; UNIVERSE
Citation Formats
BouhmadiLópez, Mariam, Brilenkov, Maxim, Brilenkov, Ruslan, Morais, João, and Zhuk, Alexander, Email: mbl@ubi.pt, Email: maxim.brilenkov@gmail.com, Email: ruslan.brilenkov@gmail.com, Email: jviegas001@ikasle.ehu.eus, Email: ai.zhuk2@gmail.com. Scalar perturbations in the late Universe: viability of the Chaplygin gas models. United States: N. p., 2015.
Web. doi:10.1088/14757516/2015/12/037.
BouhmadiLópez, Mariam, Brilenkov, Maxim, Brilenkov, Ruslan, Morais, João, & Zhuk, Alexander, Email: mbl@ubi.pt, Email: maxim.brilenkov@gmail.com, Email: ruslan.brilenkov@gmail.com, Email: jviegas001@ikasle.ehu.eus, Email: ai.zhuk2@gmail.com. Scalar perturbations in the late Universe: viability of the Chaplygin gas models. United States. doi:10.1088/14757516/2015/12/037.
BouhmadiLópez, Mariam, Brilenkov, Maxim, Brilenkov, Ruslan, Morais, João, and Zhuk, Alexander, Email: mbl@ubi.pt, Email: maxim.brilenkov@gmail.com, Email: ruslan.brilenkov@gmail.com, Email: jviegas001@ikasle.ehu.eus, Email: ai.zhuk2@gmail.com. 2015.
"Scalar perturbations in the late Universe: viability of the Chaplygin gas models". United States.
doi:10.1088/14757516/2015/12/037.
@article{osti_22525119,
title = {Scalar perturbations in the late Universe: viability of the Chaplygin gas models},
author = {BouhmadiLópez, Mariam and Brilenkov, Maxim and Brilenkov, Ruslan and Morais, João and Zhuk, Alexander, Email: mbl@ubi.pt, Email: maxim.brilenkov@gmail.com, Email: ruslan.brilenkov@gmail.com, Email: jviegas001@ikasle.ehu.eus, Email: ai.zhuk2@gmail.com},
abstractNote = {We study the latetime evolution of the Universe where dark energy (DE) is parametrised by a modified generalised Chaplygin gas (mGCG) on top of cold dark matter (CDM) . We also take into account the radiation content of the Universe. In this context, the late stage of the evolution of the universe refers to the epoch where CDM is already clustered into inhomogeneously distributed discrete structures (galaxies, groups and clusters of galaxies). Under these conditions, the mechanical approach is an adequate tool to study the Universe deep inside the cell of uniformity. To be more accurate, we study scalar perturbations of the FriedmannLemaȋtreRobertsonWalker metric due to inhomogeneities of CDM as well as fluctuations of radiation and mGCG, the later driving the latetime acceleration of the universe. Our analysis applies as well to the case where mGCG plays the role of DM and DE . We select the sets of parameters of the mGCG that are compatible with the mechanical approach. These sets define prospective mGCG models. By comparing the selected sets of models with some of the latest observational data results, we conclude that the mGCG is in tight agreement with those observations particularly for a mGCG playing the role of DE and DM.},
doi = {10.1088/14757516/2015/12/037},
journal = {Journal of Cosmology and Astroparticle Physics},
number = 12,
volume = 2015,
place = {United States},
year = 2015,
month =
}

We exploit the gaugeinvariant formalism to analyse the perturbative behaviour of two cosmological models based on the generalized Chaplygin gas describing both dark matter and dark energy in the present universe. In the first model we consider the generalized Chaplygin gas alone, while in the second one we add a baryon component to it. We extend our analysis also into the parameter range {alpha}>1, where the generalized Chaplygin gas sound velocity can be larger than that of light. In the first model we find that the matter power spectrum is compatible with the observed one only for {alpha}<10{sup 5}, whichmore »

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