Clustering and halo abundances in early dark energy cosmological models

Cold Dark Matter with cosmological constant (Lambda CDM) cosmological models with early dark energy (EDE) have been proposed to resolve tensions between the Hubble constant kms(-1)Mpc(-1) measured locally, giving h approximate to 0.73, and H-0 deduced from Planck cosmic microwave background (CMB) and other early-Universe measurements plus Lambda CDM, giving h approximate to 0.67. EDE models do this by adding a scalar field that temporarily adds dark energy equal to about 10percent of the cosmological energy density at the end of the radiation-dominated era at redshift z similar to 3500. Here, we compare linear and non-linear predictions of a Planck-normalized Lambda CDM model including EDE giving h = 0.728 with those of standard Planck-normalized Lambda CDM with h = 0.678. We find that non-linear evolution reduces the differences between power spectra of fluctuations at low redshifts. As a result, at z = 0 the halo mass functions on galactic scales are nearly the same, with differences only 1-2percent. However, the differences dramatically increase at high redshifts. The EDE model predicts 50percent more massive clusters at z = 1 and twice more galaxy-mass haloes at z = 4. Even greater increases in abundances of galaxy-mass haloes at higher redshifts may make it easier to reionize the universe with EDE. Predicted galaxy abundances and clustering will soon be tested by the James Webb Space Telescope (JWST) observations. Positions of baryonic acoustic oscillations (BAOs) and correlation functions differ by about 2percent between the models - an effect that is not washed out by non-linearities. Both standard Lambda CDM and the EDE model studied here agree well with presently available acoustic-scale observations, but the Dark Energy Spectroscopic Instrument and Euclid measurements will provide stringent new tests.

Automated summary

The Cold Dark Matter with cosmological constant (Lambda CDM) cosmological models with early dark energy (EDE) aim to resolve tensions between locally measured Hubble constant and deduced H-0 from Planck CMB data. Non-linear evolution reduces differences in power spectra at low redshifts but increases differences at high redshifts. EDE model predicts significantly more massive clusters at higher redshifts, potentially aiding in reionizing the universe.