The LABOCA survey of the Extended Chandra Deep Field-South : radio and mid-infrared counterparts to submillimetre galaxies

Abstract

We present radio and infrared (3.6-24μm) counterparts to submillimetre galaxies (SMGs) detected in the Extended Chandra Deep Field-South with the Large APEX Bolometer Camera (LABOCA) 870-μm bolometer camera on the 12-m Atacama Pathfinder Experiment. Using the Very Large Array at 1.4GHz and Spitzer, we have identified secure counterparts to 79 of the 126 SMGs [signal-to-noise ratio (S/N) > 3.7,S > 4.4mJy] in the field, 62 via their radio and/or 24-μm emission, the remainder using a colour-flux cut on Infrared Array Camera 3.6- and 5.8-μm sources chosen to maximize the number of secure, coincident radio and 24-μm counterparts. In constructing our radio catalogue, we have corrected for the effects of 'flux boosting', then used the corrected flux densities to estimate the redshifts of the SMGs based on the radio/submm spectral indices. The effect of the boosting correction is to increase the median redshift by 0.2 resulting in a value of (1σ errors) for the secure radio counterparts, in agreement with other studies, both spectroscopic and photometric.