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Speaker	Mathews, Grant
Co-autors	*X. Zhao*
Talk Title	Effects of structure formation on the apparent expansion rate of the universe: a realistic estimate based on N-body simulations
Abstract	Backreaction terms arise when the effective Friedmann equation is averaged over a spatial volume in a locally inhomogeneous cosmology. It has been suggested that these terms may contribute to the observed cosmic acceleration. Many perturbative methods for this averaging procedure have been proposed and investigated. In this paper, we first propose a new scheme that enables us to use N-body simulations to make realistic estimates of the magnitude of backreaction terms of general three dimensional inhomogeneities in space. We then quantitatively calculate the volume averaged expansion rate using an N-body simulation code and compare it with the expansion rate in a standard FRW cosmology. We also discuss the physical interpretation of the new expansion rate and its impact on other cosmological observables.
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