Current constraints on the cosmic growth history

TL;DR

This paper uses recent cosmological data to constrain deviations from Lambda CDM in the cosmic growth history, finding tight constraints on early modifications but weaker constraints on late-time deviations, consistent with standard cosmology.

Contribution

It provides a comprehensive analysis of constraints on modifications to gravity or dark energy affecting cosmic growth, combining multiple observational probes.

Findings

Early-time modifications are tightly constrained by CMB data.

Late-time modifications remain consistent with Lambda CDM at 95% confidence.

Large and small scale growth differences could help identify modified growth histories.

Abstract

We present constraints on the cosmic growth history with recent cosmological data, allowing for deviations from Lambda CDM as might arise if cosmic acceleration is due to modifications to GR or inhomogeneous dark energy. We combine measures of the cosmic expansion history, from Type 1a supernovae, baryon acoustic oscillations and the CMB, with constraints on the growth of structure from recent galaxy, CMB and weak lensing surveys along with ISW-galaxy cross-correlations. Deviations from Lambda CDM are parameterized by phenomenological modifications to the Poisson equation and the relationship between the two Newtonian potentials. We find modifications that are present at the time the CMB is formed are tightly constrained through their impact on the well-measured CMB acoustic peaks. By contrast, constraints on late-time modifications to the growth history, as might arise if modifications are related to the onset of cosmic acceleration, are far weaker, but remain consistent with Lambda CDM at the 95% confidence level. For these late-time modifications we find that differences in the evolution on large and small scales could provide an interesting signature by which to search for modified growth histories with future wide angular coverage, large scale structure surveys.