Violation of the FRW consistency condition as a signature of backreaction

TL;DR

This paper introduces a backreaction toy model that fits supernova data well, shows violation of the FRW consistency condition, and suggests this violation could serve as a signature of backreaction effects in the universe.

Contribution

It presents a realistic backreaction model that explains supernova observations and predicts observable violations of the FRW consistency condition as a signature of backreaction.

Findings

The model fits supernova data well despite differing from LCDM.

The FRW consistency condition is violated slightly below current observational limits.

Backreaction could produce observable signatures in the universe.

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.