Measuring dark energy with expansion and growth

Abstract

We combine cosmic chronometer and growth of structure data to derive the redshift evolution of the dark energy equation of state , using a novel agnostic approach. The background and perturbation equations lead to two expressions for , one purely background-based and the other relying also on the growth rate of large-scale structure. We compare the features and performance of the growth-based to the background , using Gaussian Processes for the reconstructions.