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GR: Fachverband Gravitation und Relativitätstheorie

GR 11: Kosmologie 2

GR 11.1: Vortrag

Mittwoch, 17. März 2010, 14:00–14:20, JUR K

divide et impera: Partitioning the average universe — •Alexander Wiegand¹ and Thomas Buchert² — ¹Fakultät für Physik, Universität Bielefeld, Universitätsstraße 25, D-33615 Bielefeld — ²Université Lyon 1, CRAL, 9 avenue Charles André, F-69230 Saint-Genis-Laval

Cosmological backreaction suggests a link between structure formation and the expansion history of the Universe. In order to quantitatively examine this connection we dynamically investigate a volume partition of the Universe into over– and underdense regions. This allows to trace structure formation using the volume fraction of the overdense regions λ_M as its characterizing parameter. Employing results from cosmological perturbation theory, and under the assumption of an initial near to homogeneous Gaussian density field, we construct a three–parameter model for the effective cosmic expansion history, involving λ_M0, the matter density and the Hubble rate of today’s Universe.

The talk presents the resulting model and first tests of its capability to explain what we know about the evolution of the Universe, in the backreaction context. Furthermore, the possible benefits of an application of the partitioning approach to more general cases will be discussed.