The Canada‐UK Deep Submillimeter Survey: First Submillimeter Images, the Source Counts, and Resolution of the Background

We present the first results of a deep unbiased submillimetre survey carriedout at 450 and 850 microns. We detected 12 sources at 850 microns, giving asurface density of sources with 850-micron flux densities > 2.8mJy of of0.49+-0.16 per square arcmin. The sources constitute 20-30% of the backgroundradiation at 850 microns and thus a significant fraction of the entirebackground radiation produced by stars. This implies, through the connectionbetween metallicity and background radiation, that a significant fraction ofall the stars that have ever been formed were formed in objects like thosedetected here. The combination of their large contribution to the backgroundradiation and their extreme bolometric luminosities make these objectsexcellent candidates for being proto-ellipticals. Optical astronomers haverecently shown that the UV-luminosity density of the universe increases by afactor of about 10 between z=0 and z=1 and then decreases again at higherredshifts. Using the results of a parallel submillimetre survey of the localuniverse, we show that both the submillimetre source density and background canbe explained if the submillimetre luminosity density evolves in a similar wayto the UV-luminosity density. Thus, if these sources are ellipticals in theprocess of formation, they may be forming at relatively modest redshifts.Comment: 8 pages (LATEX), 6 postscript figures, submitted to ApJ Letter