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arXiv · 1308.1119

A submillimetre-bright z~3 overdensity behind a z~1 supercluster revealed by SCUBA-2 and Herschel

A. G. Noble·J. E. Geach·A. J. van Engelen·T. M. A. Webb·K. E. K. Coppin·A. Delahaye·D. G. Gilbank·M. D. Gladders·R. J. Ivison·Y. Omori·H. K. C. Yee
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Abstract

We present a wide-field (30' diameter) 850um SCUBA-2 map of the spectacular three-component merging supercluster, RCS 231953+00, at z=0.9. The brightest submillimetre galaxy (SMG) in the field (S_850=12mJy) is within 30" of one of the cluster cores (RCS 2319-C), and is likely to be a more distant, lensed galaxy. Interestingly, the wider field around RCS 2319-C reveals a local overdensity of SMGs, exceeding the average source density by a factor of 4.5, with a <1 per cent chance of being found in a random field. Utilizing Herschel-SPIRE observations, we find three of these SMGs have similar submillimetre colours. We fit their observed 250-850um spectral energy distributions to estimate their redshift, yielding 2.5<z<3.5, and calculate prodigious star formation rates (SFRs) ranging from 500-2500 solar masses per year. We speculate that these galaxies are either lensed SMGs, or signpost a physical structure at z~3: a 'protocluster' inhabited by young galaxies in a rapid phase of growth, destined to form the core of a massive galaxy cluster by z=0.

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A. G. Noble, J. E. Geach, A. J. van Engelen, T. M. A. Webb, K. E. K. Coppin, A. Delahaye, D. G. Gilbank, M. D. Gladders, R. J. Ivison, Y. Omori, H. K. C. Yee. 2013-08-05. A submillimetre-bright z~3 overdensity behind a z~1 supercluster revealed by SCUBA-2 and Herschel. https://doi.org/10.1093/mnrasl%2Fslt108

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