Chaplygin gas and effective description of inhomogeneous universe models in general relativity - General Relativity and Quantum CosmologyReport as inadecuate




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Abstract: In the framework of spatially averaged inhomogeneous cosmologies in classicalgeneral relativity, effective Einstein equations govern the dynamics ofaveraged scalar variables in a scale-dependent way. A particular cosmology maybe characterized by a cosmic equation of state, closing the hierarchy ofeffective equations. In this context a natural candidate is provided by theChaplygin gas, standing for a unified description of dark energy and darkmatter. In this paper, we suppose that the inhomogeneous properties of matterand geometry obey the Chaplygin equation of state. The most extremeinterpretation assumes that both dark energy and dark matter are not includedas additional sources, but are both manifestations of spatial geometricalproperties. This feature is an important conceptual difference in comparisonwith the standard approach of a Friedmann-Lema\^itre-Robertson-Walker universefilled with dust and another fundamental field characterized by the Chaplyginequation of state. We finally discuss the consequences of the resultingscenario for effective cosmological parameters in order to establish theframework of a future confrontation with observations, and we note that thestandard Chaplygin gas may not be ruled out by them.



Author: Xavier Roy, Thomas Buchert

Source: https://arxiv.org/



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