A combined re-analysis of existing blank-field SCUBA surveys: comparative 850-micron source lists, combined number counts, and evidence for strong clustering of the bright sub-mm galaxy population

Abstract

Taken together, the blank-field sub-mm surveys undertaken with SCUBA prior to the SHADES survey cover a total area of 460 sq. arcmin to a range of depths. However combining the results from these surveys has hitherto been complicated by the fact that different survey groups have used different methods of data reduction and source extraction. Here we present the results of re-reducing and analysing all of these blank field SCUBA in an almost identical manner to that employed in the SCUBA 8-mJy Survey. Comparative source catalogues are given which include a number of new significant source detections as well as failing to confirm some of those objects previously published. These new source catalogues have been combined to produce the most accurate number counts to date from 2 to 12.5 mJy. The cumulative number counts appear to steepen beyond S(850)=8mJy, which could indicate an intrinsic turn-over in the underlying luminosity function placing an upper limit on the luminosity (and hence mass) of a high redshift galaxy. We have also investigated the clustering properties of the bright SCUBA population by means of 2-point angular correlation functions. We find evidence for strong clustering broadly consistent with that measured for Extremely Red Objects (EROs). Nearest-neighbour analyses further support strong clustering on arcmin scales, rejecting the null hypothesis that the distribution of the bright submm sources is random at the 99% confidence level.