Measurements of Sunyaev‐Zel’dovich Effect Scaling Relations for Clusters of Galaxies

Abstract

We present new measurements of the Sunyaev-Zel'dovich (SZ) effect from clusters of galaxies using the second-generation Sunyaev-Zel'dovich Infrared Experiment (SuZIE II). We combine these new measurements with previous cluster observations with the SuZIE instrument to form a sample of 15 clusters of galaxies. For this sample we calculate the central Comptonization y0 and the integrated SZ flux decrement S for each of our clusters. We find that the integrated SZ flux is a more robust observable derived from our measurements than the central Comptonization because of inadequacies in the spatial modeling of the intracluster gas with a standard β-model. This is highlighted by comparing our central Comptonization results with values calculated from measurements using the BIMA and OVRO interferometers. On average, the SuZIE-calculated central Comptonizations are ~60% higher in the cooling flow clusters than the interferometric values, compared to only ~12% higher in the non-cooling flow clusters. We believe this discrepancy to be in large part due to the spatial modeling of the intracluster gas. From our cluster sample we construct y0-T and S-T scaling relations. The y0-T scaling relation is inconsistent with what we would expect for self-similar clusters; however, this result is questionable because of the large systematic uncertainty in y0. The S-T scaling relation has a slope and redshift evolution consistent with what we expect for self-similar clusters, with a characteristic density that scales with the mean density of the universe. We rule out zero-redshift evolution of the S-T relation at ~90% confidence.