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arXiv · astro-ph/0507285

A VSA search for the extended Sunyaev-Zel'dovich Effect in the Corona Borealis Supercluster

Ricardo Genova-Santos·Jose Alberto Rubino-Martin·Rafael Rebolo·Kieran Cleary·Rod D. Davies·Richard J. Davis·Clive Dickinson·Nelson Falcon·Keith Grainge·Carlos M. Gutierrez·Michael P. Hobson·Michael E. Jones·Ruediger Kneissl·Katy Lancaster·Carmen P. Padilla-Torres·Richard D. E. Saunders·Paul F. Scott·Angela C. Taylor·Robert A. Watson
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Abstract

We present interferometric imaging at 33 GHz of the Corona Borealis supercluster, using the extended configuration of the Very Small Array. A total area of 24 deg^2 has been imaged, with an angular resolution of 11 arcmin and a sensitivity of 12 mJy/beam. The aim of these observations is to search for Sunyaev-Zel'dovich (SZ) detections from known clusters of galaxies in this supercluster and for a possible extended SZ decrement due to diffuse warm/hot gas in the intercluster medium. We measure negative flux values in the positions of the ten richest clusters in the region. Collectively, this implies a 3.0-sigma detection of the SZ effect. In the clusters A2061 and A2065 we find decrements of approximately 2-sigma. Our main result is the detection of two strong and resolved negative features at -70+-12 mJy/beam (-157+-27 microK) and -103+-10 mJy/beam (-230+-23 microK), respectively, located in a region with no known clusters, near the centre of the supercluster. We discuss their possible origins in terms of primordial CMB anisotropies and/or SZ signals related to either unknown clusters or to a diffuse extended warm/hot gas distribution. Our analyses have revealed that a primordial CMB fluctuation is a plausible explanation for the weaker feature (probability of 37.82%). For the stronger one, neither primordial CMB (probability of 0.33%) nor SZ can account alone for its size and total intensity. The most reasonable explanation, then, is a combination of both primordial CMB and SZ signal. Finally, we explore what characteristics would be required for a filamentary structure consisting of warm/hot diffuse gas in order to produce a significant contribution to such a spot taking into account the constraints set by X-ray data.

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Ricardo Genova-Santos, Jose Alberto Rubino-Martin, Rafael Rebolo, Kieran Cleary, Rod D. Davies, Richard J. Davis, Clive Dickinson, Nelson Falcon, Keith Grainge, Carlos M. Gutierrez, Michael P. Hobson, Michael E. Jones, Ruediger Kneissl, Katy Lancaster, Carmen P. Padilla-Torres, Richard D. E. Saunders, Paul F. Scott, Angela C. Taylor, Robert A. Watson. 2005-07-12. A VSA search for the extended Sunyaev-Zel'dovich Effect in the Corona Borealis Supercluster. https://doi.org/10.1111/j.1365-2966.2005.09405.x

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