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

Abstract

In the standard A 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 -0.05 , 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 X 2 / 1 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.