Measuring dark energy with expansion and growth

Understand

We combine cosmic chronometer and growth of structure data to derive the redshift evolution of the dark energy equation of state $w$, using a novel agnostic approach.

• The background and perturbation equations lead to two expressions for $w$, 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 $w$ to the background $w$, using Gaussian Processes for the reconstructions.
• We find that current data is not precise enough for robust reconstruction of the two forms of $w$.