Submillimeter detection of the Sunyaev – Zel ’ dovich effect toward the most luminous X - ray cluster at z = 0 . 45

We report on the detection of the Sunyaev – Zel’dovich (SZ) signals toward the most luminous X-ray cluster RXJ1347-1145 at Nobeyama Radio Observatory (21 and 43 GHz) and at James Clerk Maxwell Telescope (350 GHz). In particular the latter is the first successful detection of the SZ temperature increment in the submillimeter band which resolved the profile of a cluster of galaxies. Both the observed spectral dependence and the radial profile of the SZ signals are fully consistent with those expected from the X-ray observation of the cluster. The combined analysis of 21GHz and 350GHz data reproduces the temperature and core-radius of the cluster determined with the ROSAT and ASCA satellites when we adopt the slope of the density profile from the X-ray observations. Therefore our present data provide the strongest and most convincing case for the detection of the submillimeter SZ signal from the cluster, as well as in the Rayleigh – Jeans regime. We also discuss briefly the cosmological implications of the present results. Subject headings: cosmology: observations – distance scale – cosmic microwave background – galaxies: clusters: individual (RXJ1347-1145) – X-rays: galaxies The Astrophysical Journal (Letters), in press Astronomical Institute, Tôhoku University, Aoba, Sendai 980-8578, Japan Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan Research Center for the Early University, School of Science, The University of Tokyo, Tokyo 113-0033, Japan Nobeyama Radio Observatory, Minamimaki, Minamisaku, Nagano 384-1305, Japan Astrophysics Research Institute, Liverpool John Moores University, Byrom Street, Liverpool L3 3AF, UK Department of Astronomy, Kyoto University, Kyoto 606-8502, Japan