Model independent tests of cosmic growth versus expansion

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 Baryon Oscillation Spectroscopic Survey 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. © 2013 American Physical Society.