Parameter splitting in dark energy: is dark energy the same in the background and in the cosmic structures?

Understand

We perform an empirical consistency test of General Relativity/dark energy by disentangling expansion history and growth of structure constraints.

• We replace each late-universe parameter that describes the behavior of dark energy with two meta-parameters: one describing geometrical information in cosmological probes, and the other controlling the growth of structure.
• If the underlying model (a standard wCDM cosmology with General Relativity) is correct, that is under the null hypothesis, the two meta-parameters coincide.
• If they do not, it could indicate a failure of the model or systematics in the data.