Statistics of the Sunyaev-Zel'dovich Effect power spectrum

TL;DR

This study uses simulations to analyze the statistical properties of the Sunyaev-Zel'dovich effect power spectrum, revealing increased variance and skewness, and discusses implications for cosmic microwave background measurements and cosmological parameters.

Contribution

It provides a detailed statistical analysis of the SZ effect power spectrum from simulations, highlighting non-Gaussian features and their impact on CMB observations, which was not thoroughly characterized before.

Findings

SZ power spectrum has a standard deviation 3 times larger than Gaussian predictions.

Distribution of the SZ spectrum is significantly skewed towards higher values.

Clustering increases the standard deviation by about 10%."],

Abstract

Using large numbers of simulations of the microwave sky, incorporating the Cosmic Microwave Background (CMB) and the Sunyaev-Zel'dovich (SZ) effect due to clusters, we investigate the statistics of the power spectrum at microwave frequencies between spherical multipoles of 1000 and 10000. From these virtual sky maps, we find that the spectrum of the SZ effect has a larger standard deviation by a factor of 3 than would be expected from purely Gaussian realizations, and has a distribution that is significantly skewed towards higher values, especially when small map sizes are used. The standard deviation is also increased by around 10 percent compared to the trispectrum calculation due to the clustering of galaxy clusters. We also consider the effects of including residual point sources and uncertainties in the gas physics. This has implications for the excess power measured in the CMB power spectrum by the Cosmic Background Imager and BIMA experiments. Our results indicate that the observed excess could be explained using a lower value of $\sigma_8$ than previously suggested, however the effect is not enough to match $\sigma_8=0.825$. The uncertainties in the gas physics could also play a substantial role. We have made our maps of the SZ effect available online.