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Title: Backreaction mechanism in multifluid and extended cosmologies

One possible explanation for the present observed acceleration of the Universe is the breakdown of homogeneity and isotropy due to the formation of non-linear structures. How inhomogeneities affect the averaged cosmological expansion rate and lead to late-time acceleration is generally considered to be due to some backreaction mechanism. In the recent literature most averaging calculations have focused their attention on General Relativity together with pressure-free matter. In this communication we focus our attention on more general scenarios, including imperfect fluids as well as alternative theories of gravity, and apply an averaging procedure to them in order to determine possible backreaction effects. For illustrative purposes, we present our results for dark energy models, quintessence and Brans-Dicke theories. We also provide a discussion about the limitations of frame choices in the averaging procedure.
Authors:
 [1] ;  [2] ; ;  [3]
  1. Centre for Cosmology, Particle Physics and Phenomenology, Institute of Mathematics and Physics, Louvain University, 2 Chemin du Cyclotron, 1348 Louvain-la-Neuve (Belgium)
  2. Departamento de Física Teórica I, Ciudad Universitaria, Universidad Complutense de Madrid, E-28040 Madrid (Spain)
  3. Astrophysics, Cosmology and Gravity Centre (ACGC), University of Cape Town, Rondebosch 7701, Cape Town (South Africa)
Publication Date:
OSTI Identifier:
22373567
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2014; Journal Issue: 05; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; ACCELERATION; COMMUNICATIONS; COSMOLOGY; EXPANSION; FLUIDS; GENERAL RELATIVITY THEORY; GRAVITATION; ISOTROPY; NONLINEAR PROBLEMS; NONLUMINOUS MATTER; UNIVERSE