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

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 ΔT0 = -179 ± 38, -33 ± 81, and 170 ± 35 μK in the cluster center. The corresponding optical depth, τ = (4.1 ± 0.9) × 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.