Accelerated-like expansion: inhomogeneities versus dark energy

Abstract

The currently available cosmological data yield, as a most striking result, that the expansion rate of the universe seems to be increasing at late times, contrary to the standard (zero cosmological constant) FLRW prediction. The usual explanation for this discrepancy is that a new component of the energy density of the universe, known as dark energy, dominates this recent evolution. Since the existence of such a new component would have a revolutionary impact on our understanding of the fundamental laws of physics, we think important to check other interpretations. We have therefore shown that the SNIa observations could be reproduced by the effect of inhomogeneities. This idea has been further developed by different teams, and enlarged to other cosmological data. We will give here a review of the results of these works and the prospects for future developments.