Cluster abundances and Sunyaev-Zel'dovich power spectra: effects of non-Gaussianity and early dark energy

In the standard Lambda cold dark matter cosmological model with a Gaussian primordial density fluctuation field, the relatively low value of the mass variance parameter (sigma(8) = 0.74(-0.06)(+0.05), obtained from the Wilkinson Microwave Anisotropy Probe three-year data) results in a reduced likelihood that the measured level of cosmic microwave background anisotropy on the scales of clusters is due to the Sunyaev-Zel'dovich (S-Z) effect. To assess the feasibility of producing higher levels of S-Z power, we explore two alternative models which predict higher cluster abundance. In the first model the primordial density field has a