VSA Results. A Survey in the Corona Borealis Supercluster
We present interferometric imaging at 33 GHz of the Corona Borealis supercluster, using the extended VSA. A total area of 24 deg² has been imaged, with an angular resolution of 11 arcmin and a sensitivity of 12 mJy/beam. The aim of these observations was to search for Sunyaev-Zel'dovich (SZ) detections from known cluster of galaxies in this supercluster, and for a possible extended SZ decrement due to diffuse warm/hot gas in the inter-cluster medium. Hydrodynamical simulations suggest that a significant part of the missing baryons in the local universe may be located in superclusters.
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The analysis of the maps constructed from these observations have revealed the existence of an strong and resolved negative feature at -103±10 mJy/beam (-231±-23 µK), located in a region with no known clusters, near the optical centre of the supercluster. Statistical studies show that this feature is strongly non-Gaussian. We find that the most reasonable explanation for its origin is a combination of both primordial CMB and SZ signal. For details, see Génova-Santos et al. (2005).
(July 2005)