On the Angular Correlation Function of SZ Clusters : Extracting cosmological information from a 2D catalog

We discuss the angular correlation function of Sunyaev–Zel’dovich (SZ)–detected galaxy clusters as a cosmological probe. As a projection of the real–space cluster correlation function, the angular function samples the underlying SZ catalog redshift distribution. It offers a way to study cosmology and cluster evolution directly with the two–dimensional catalog, even before extensive follow–up observations, thereby facilitating the immediate scientific return from SZ surveys. As a simple illustration of the information content of the angular function, we examine its dependence on the parameter pair (ΩM, σ8) in flat cosmologies. We discuss sources of modeling uncertainty and consider application to the future Planck SZ catalog, showing how these two parameters and the normalization of the SZ flux–mass relation can be simultaneously found when the local X–ray cluster abundance constraint is included.