MEASUREMENT OF THE SUNYAEV-ZELDOVICH EFFECT TOWARD ABELL-2163 AT A WAVELENGTH OF 2.2 MILLIMETERS

We report the first significant detection of the Sunyaev-Zel'dovich (S-Z) effect at millimeter wavelengths. Drift scans of the cluster of galaxies Abell 2163 were performed using a novel bolometric array receiver at a wavelength of 2.2 millimeters. The measured decrement in sky brightness corresponds to a peak Comptonization of the cosmic microwave background radiation at the cluster of center y = (3.78(0.74/-0.65)) x 10(-4). Measurements at millimeter wavelengths are necessary to separate the thermal and kinetic S-Z effects. The value of the Hubble constant can be derived from the amplitude of the thermal effect in combination with the measured X-ray properties of the cluster. The radial peculiar velocity of the cluster relative to its local CMB rest frame can be derived from the relative amplitude of the kinetic and thermal effects and the X-ray temperature.