Cosmological backreaction for a test field observer in a chaotic inflationary model

In an inhomogeneous universe, an observer associated with a particular matter field does not necessarily measure the same cosmological evolution as an observer in a homogeneous and isotropic universe. Here we consider, in the context of a chaotic inflationary background model, a class of observers a...

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Bibliographic Details
Published in:Journal of cosmology and astroparticle physics 2013-02, Vol.2013 (2), p.27-27
Main Authors: Marozzi, Giovanni, Vacca, Gian Paolo, Brandenberger, and Robert H
Format: Article
Language:English
Subjects:
APPROXIMATIONS
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
CHAOS THEORY
COSMOLOGY
EQUATIONS OF STATE
EVOLUTION
EXPANSION
FLUCTUATIONS
GAUGE INVARIANCE
PERTURBATION THEORY
STOCHASTIC PROCESSES
UNIVERSE
VISIBLE RADIATION
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Summary:In an inhomogeneous universe, an observer associated with a particular matter field does not necessarily measure the same cosmological evolution as an observer in a homogeneous and isotropic universe. Here we consider, in the context of a chaotic inflationary background model, a class of observers associated with a ''clock field'' for which we use a light test field. We compute the effective expansion rate and fluid equation of state in a gauge invariant way, taking into account the quantum fluctuations of the long wavelength modes, and working up to second order in perturbation theory and in the slow-roll approximation. We find that the effective expansion rate is smaller than what would be measured in the absence of fluctuations. Within the stochastic approach we study the bounds for which the approximations we make are consistent.
ISSN:1475-7516
1475-7516
DOI:10.1088/1475-7516/2013/02/027