Coppin, K. E. K.; Geach, J. E.; Smail, Ian; Dunne, L.; Edge, A. C.; Ivison, R. J.; Maddox, S.; Auld, R.; Baes, M.; Buttiglione, S.; Cava, A.; Clements, D. L.; Cooray, A.; Dariush, A.; De Zotti, G.; Dye, S.; Eales, S.; Fritz, J.; Hopwood, R.; Ibar, E.; Jarvis, M.; Michałowski, M. J.; Murphy, D. N. A.; Negrello, M.; Pascale, E.; Pohlen, M.; Rigby, E.; Rodighiero, G.; Scott, D.; Serjeant, S.; Smith, D. J. B.; Temi, P. and van der Werf, P.
Herschel-Astrophysical Terahertz Large Area Survey: detection of a far-infrared population around galaxy clusters.
Monthly Notices of the Royal Astronomical Society, 416(1) pp. 680–688.
We report the detection of a significant excess in the surface density of far-infrared sources from the Herschel-Astrophysical Terahertz Large Area Survey within ∼1 Mpc of the centres of 66 optically selected clusters of galaxies in the Sloan Digital Sky Survey with 〈z〉∼ 0.25. From the analysis of the multiwavelength properties of their counterparts we conclude that the far-infrared emission is associated with dust-obscured star formation and/or active galactic nuclei (AGN) within galaxies in the clusters themselves. The excess reaches a maximum at a radius of ∼0.8 Mpc, where we find 1.0 ± 0.3 S250 > 34 mJy sources on average per cluster above what would be expected for random field locations. If the far-infrared emission is dominated by star formation (as opposed to AGN) then this corresponds to an average star formation rate of ∼7 M⊙ yr−1 per cluster in sources with LIR > 5 × 1010 L⊙. Although lensed sources make a negligible contribution to the excess signal, a fraction of the sources around the clusters could be gravitationally lensed, and we have identified a sample of potential cases of cluster-lensed Herschel sources that could be targeted in follow-up studies.
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