The hybrid SZ power spectrum: combining cluster counts and SZ fluctuations to probe gas physics

The Sunyaev-Zeldovich (SZ) effect from a cosmological distribution of clusters carries information on the underlying cosmology, as well as on the clusters' gas physics. In order to study either cosmology or clusters one needs to break the degeneracies between the two. We present a toy model showing how complementary information from the SZ power spectrum and SZ flux counts, both obtained from upcoming SZ cluster surveys, can be used to mitigate the strong cosmological influence (especially that of sigma (8)) on the SZ fluctuations. Once the strong dependence of the cluster SZ power spectrum on sigma (8) is diluted, the cluster power spectrum can be used as a tool to study the cluster's gas physics and its evolution. The method relies on the ability to write the Poisson contribution to the SZ power spectrum in terms of the observed SZ flux counts (hybrid power spectrum). The correlation term can be estimated as the difference between an observed power spectrum and the hybrid power spectrum. We test the algorithm with simulations of SZ surveys.