Wednesday, March 20, 2013

1303.4444 (Boudewijn F. Roukema et al.)

Virialization-induced curvature as a physical explanation for dark energy    [PDF]

Boudewijn F. Roukema, Jan J. Ostrowski, Thomas Buchert
The geometry of the dark-energy and cold dark matter dominated cosmological model (LambdaCDM) is commonly assumed to be given by a Friedmann-Lema^itre-Robertson-Walker (FLRW) metric, i.e. it assumes homogeneity in the comoving spatial section. The FLRW approximation is expected to fail at (i) small distance scales and (ii) recent epochs. We use the virialization fraction to quantify (i) and (ii), which approximately coincide with each other on the observational past light cone. For increasing time, the virialization fraction increases above 10% at about the same redshift (sim 1-3) at which Omega_Lambda grows above 10% (approx 1.8). Thus, instead of non-zero Omega_Lambda, we propose an approximate, general-relativistic correction to the matter-dominated (Omm =1, Omega_Lambda=0), homogeneous metric (Einstein-de Sitter, EdS). Over redshifts 0 < z < 3, about 51-82% of the distance modulus separating the LambdaCDM model from the uncorrected EdS model is provided by the approximation proposed here. This rough approximation assumes "old physics" (general relativity), not "new physics". Thus, pending more detailed, relativistic calculations, we strengthen the claim that "dark energy" should be considered as an artefact of emerging average curvature in the void-dominated Universe, via a novel approach that quantifies the relation between virialization and average curvature evolution.
View original: http://arxiv.org/abs/1303.4444

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