Violation of the FRW consistency condition as a signature of backreaction

Abstract

We propose a backreaction toy model with realistic features and confront it with the Union2.1 supernova data. The model provides a good fit even though the expansion history is quite different from the LCDM model and the effective equation of state is far from -1. We discuss compatibility (or lack thereof) with other observations. We show that the FRW consistency condition between distance and expansion rate is violated with an amplitude that is slightly below the current observational limits. We expect that this is also the case in the real universe if backreaction is significant, providing a distinct signature of backreaction.