THE LARGE APEX BOLOMETER CAMERA SURVEY OF THE EXTENDED CHANDRA DEEP FIELD SOUTH

Abstract

We present a sensitive 870 micron survey of the Extended Chandra Deep Field\nSouth (ECDFS) using LABOCA on the APEX telescope. The LABOCA ECDFS\nSubmillimetre Survey (LESS) covers the full 30' x 30' field size of the ECDFS\nand has a uniform noise level of 1.2 mJy/beam. LESS is thus the largest\ncontiguous deep submillimetre survey undertaken to date. The noise properties\nof our map show clear evidence that we are beginning to be affected by\nconfusion noise. We present a catalog of 126 SMGs detected with a significance\nlevel above 3.7 sigma. The ECDFS exhibits a deficit of bright SMGs relative to\npreviously studied blank fields but not of normal star-forming galaxies that\ndominate the extragalactic background light (EBL). This is in line with the\nunderdensities observed for optically defined high redshift source populations\nin the ECDFS (BzKs, DRGs,optically bright AGN and massive K-band selected\ngalaxies). The differential source counts in the full field are well described\nby a power law with a slope of alpha=-3.2, comparable to the results from other\nfields. We show that the shape of the source counts is not uniform across the\nfield. The integrated 870 micron flux densities of our source-count models\naccount for >65% of the estimated EBL from COBE measurements. We have\ninvestigated the clustering of SMGs in the ECDFS by means of a two-point\ncorrelation function and find evidence for strong clustering on angular scales\n<1'. Assuming a power law dependence for the correlation function and a typical\nredshift distribution for the SMGs we derive a spatial correlation length of\nr_0=13+/-6 h^-1 Mpc.\n