Model Independent Tests of Cosmic Growth vs Expansion

TL;DR

This paper employs Gaussian Processes to reconstruct the universe's expansion and growth histories in a model-independent way, testing gravity against observational data and finding results consistent with general relativity.

Contribution

It introduces a novel, model-independent method to compare cosmic growth and expansion histories using Gaussian Processes and large-scale structure data.

Findings

Results are consistent with general relativity.

No significant deviations from GR in growth measurements.

Method provides a new way to test gravity independently of dark energy models.

Abstract

We use Gaussian Processes to map the expansion history of the universe in a model independent manner from the Union2.1 supernovae data and then apply these reconstructed results to solve for the growth history. By comparing this to BOSS and WiggleZ large scale structure data we examine whether growth is determined wholly by expansion, with the measured gravitational growth index testing gravity without assuming a model for dark energy. A further model independent analysis looks for redshift dependent deviations of growth from the general relativity solution without assuming the growth index form. Both approaches give results consistent with general relativity.