An AzTEC 1.1 mm survey of the GOODS-N field - II. Multiwavelength identifications and redshift distribution

We present results from a multiwavelength study of 29 sources (false detection probabilities <5 per cent) from a survey of the Great Observatories Origins Deep Survey-North (GOODS-N) field at 1.1 mm using the Astronomical Thermal Emission Camera (AzTEC). Comparing with existing 850 mu m Submillimetre Common-User Bolometer Array (SCUBA) studies in the field, we examine differences in the source populations selected at the two wavelengths. The AzTEC observations uniformly cover the entire survey field to a 1 sigma depth of similar to 1 mJy. Searching deep 1.4 GHz Very Large Array (VLA) and Spitzer 3-24 mu m catalogues, we identify robust counterparts for 21 1.1mm sources, and tentative associations for the remaining objects. The redshift distribution of AzTEC sources is inferred from available spectroscopic and photometric redshifts. We find a median redshift of z = 2.7, somewhat higher than z = 2.0 for 850 mu m selected sources in the same field, and our lowest redshift identification lies at a spectroscopic redshift z = 1.1460. We measure the 850 mu m to 1.1mm colour of our sources and do not find evidence for '850 mu m dropouts', which can be explained by the low signal-to-noise ratio of the observations. We also combine these observed colours with spectroscopic redshifts to derive the range of dust temperatures T, and dust emissivity indices beta for the sample, concluding that existing estimates T similar to 30 K and beta similar to 1.75 are consistent with these new data.