Testing averaged cosmology with type Ia supernovae and BAO data

TL;DR

This paper evaluates averaged cosmological models using supernovae and BAO data, finding evidence for non-trivial spatial curvature and favoring these models over standard CDM in a Bayesian analysis.

Contribution

It introduces a simple two-scale backreaction model with decoupled curvature parameters and assesses its observational viability with current data.

Findings

Averaged cosmologies are favored over CDM with current data.

Evidence for non-trivial spatial curvature is found.

Bayesian model selection supports the averaged models.

Abstract

An important problem in precision cosmology is the determination of the effects of averaging and backreaction on observational predictions, particularly in view of the wealth of new observational data and improved statistical techniques. In this paper, we discuss the observational viability of a class of averaged cosmologies which consist of a simple parametrized phenomenological two-scale backreaction model with decoupled spatial curvature parameters. We perform a Bayesian model selection analysis and find that this class of averaged phenomenological cosmological models is favored with respect to the standard $\Lambda$CDM cosmological scenario when a joint analysis of current SNe Ia and BAO data is performed. In particular, the analysis provides observational evidence for non-trivial spatial curvature.