Clustering and Halo Abundances in Early Dark Energy Cosmological Models
  LCDM cosmological models with Early Dark Energy (EDE) have been proposed to
resolve tensions between the Hubble constant H0 = 100h km/s/Mpc measured
locally, giving h ~ 0.73, and H0 deduced from Planck cosmic microwave
background (CMB) and other early universe measurements plus LCDM, giving h ~
0.67. EDE models do this by adding a scalar field that temporarily adds dark
energy equal to about 10% of the cosmological energy density at the end of the
radiation-dominated era at redshift z ~ 3500. Here we compare linear and
nonlinear predictions of a Planck-normalized LCDM model including EDE giving h
= 0.728 with those of standard Planck-normalized LCDM with h = 0.678. We find
that nonlinear 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 1-2%. However, the
differences dramatically increase at high redshifts. The EDE model predicts 50%
more massive clusters at z = 1 and twice more galaxy-mass halos at z = 4. Even
greater increases in abundances of galaxy-mass halos at higher redshifts may
make it easier to reionize the universe with EDE. Predicted galaxy abundances
and clustering will soon be tested by JWST observations. Positions of baryonic
acoustic oscillations (BAOs) and correlation functions differ by about 2%
between the models -- an effect that is not washed out by nonlinearities. Both
standard LCDM and the EDE model studied here agree well with presently
available acoustic-scale observations, but DESI and Euclid measurements will
provide stringent new tests.
