Mapping the Evolution of High-Redshift Dusty Galaxies with Submillimeter Observations of a Radio-selected Sample

Direct submm imaging has recently revealed the 850-micron background to bemostly composed of a population of distant ultraluminous infrared galaxies, butidentifying the optical/NIR counterparts to these sources has proved difficultdue to the poor submm spatial resolution. However, the proportionality of bothcm and submm data to the star formation rate suggests that high resolutionradio continuum maps with subarcsecond positional accuracy can be exploited tolocate submm sources. In this paper we present results from a targeted SCUBAsurvey of micro-Jansky radio sources in the flanking fields of the Hubble DeepField. Even with relatively shallow 850-micron SCUBA observations (>6 mJy at3-sigma), we were successful at making submm detections of optical/NIR-faint(I>24 and K~21-22) radio sources, and our counts closely match the brightcounts from submm surveys. Redshift estimates can be made from the ratio of thesubmm flux to the radio flux across the 100 GHz break in the spectral energydistribution. This millimetric redshift estimation places the bright submmpopulation at z=1-3 where it forms the high redshift tail of the faint radiopopulation. The star formation rate density (SFRD) due to ultraluminousinfrared galaxies increases by more than two orders of magnitude from z~0 toz~1-3. The SFRD at high redshift inferred from our >6 mJy submm observations iscomparable to that observed in the UV/optical. (Abridged)Comment: 18 pages, accepted by The Astronomical Journal for April 2000 issu