MITO Measurements of the Sunyaev-Zeldovich Effect in the Coma Cluster of Galaxies

Abstract

We have measured the Sunyaev-Zeldovich (SZ) effect toward the Coma Cluster (A1656) with the Millimetre and Infrared Testagrigia Observatory experiment, a 2.6 m telescope equipped with a four-channel 17' (FWHM) photometer. Measurements at frequency bands 143+/-15, 214+/-15, 272+/-16, and 353+/-13 GHz were made during 120 drift scans of Coma. We describe the observations and data analysis that involved extraction of the SZ signal by employing a spatial and spectral decorrelation scheme to remove a dominant atmospheric component. The deduced values of the thermal SZ effect in the first three bands are DeltaT(0) = -179+/-38, -33+/-81, and 170+/-35 muK in the cluster center. The corresponding optical depth, tau = (4.1+/-0.9) x 10(-3), is consistent (within errors) with both the value from a previous low-frequency SZ measurement and the value predicted from the X-ray-deduced gas parameters.