The nature of the bright submillimeter galaxy population: A radio-preselected sample with I >similar to 25

Deep submillimeter surveys have successfully detected distant, star-forming galaxies, which are enshrouded in vast quantities of dust and emit most of their energy at far-infrared wavelengths. These luminous galaxies are an i mportant constituent of the universal star formation history, and any compl ete model of galaxy evolution must account for their existence. Although th ese sources have been tentatively identified with very faint and sometimes very red optical counterparts, their poorly constrained redshift distributi on has made their interpretation unclear. In particular, it was not underst ood if these galaxies had been missed in previous surveys or if they consti tuted a truly new class of objects, undetectable at other wavelengths. By u tilizing a radio selection technique, we have isolated a sample of 20 submi llimeter objects representative of the 850 mum population brighter than 5 m Jy with. We show that these galaxies are so heavily dust-obscured that they remain essentially "invisible" z less than or similar to 3 to ultraviolet selection. Furthermore, relying on the radio/submillimeter flux density rat io, we estimate their redshift distribution, finding a median of two. These results are inconsistent with the existence of a very high redshift (z > 4 ) population of primeval galaxies (L-bol > 10(12) L-.) contributing substan tially to the submillimeter counts. While not a substitute for the thorough follow- up of blank-field submillimeter surveys, our results do shed light on a substantial portion of the luminous submillimeter population with. z less than or similar to 3.