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

ABSTRACT In the standard Λ cold dark matter cosmological model with a Gaussian primordial density fluctuation field, the relatively low value of the mass variance parameter (σ₈ = 0.74^+0.05 _-0.06, 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 χ²₁ distribution, whereas in the second an early dark energy component gives rise to the desired higher cluster abundance. We carry out the necessary detailed calculations of the levels of S-Z power spectra, cluster number counts, and angular two-point correlation function of clusters, and compare (in a self-consistent way) their predicted redshift distributions. Our results provide a sufficient basis on which the viability of the three models may be tested by future high-quality measurements.