EXTRAGALACTIC MILLIMETER-WAVE SOURCES IN SOUTH POLE TELESCOPE SURVEY DATA: SOURCE COUNTS, CATALOG, AND STATISTICS FOR AN 87 SQUARE-DEGREE FIELD

Abstract

We report the results of an 87 square-degree point-source survey centered at\nR.A. 5h30m, decl. -55 deg. taken with the South Pole Telescope (SPT) at 1.4 and\n2.0 mm wavelengths with arc-minute resolution and milli-Jansky depth. Based on\nthe ratio of flux in the two bands, we separate the detected sources into two\npopulations, one consistent with synchrotron emission from active galactic\nnuclei (AGN) and one consistent with thermal emission from dust. We present\nsource counts for each population from 11 to 640 mJy at 1.4 mm and from 4.4 to\n800 mJy at 2.0 mm. The 2.0 mm counts are dominated by synchrotron-dominated\nsources across our reported flux range; the 1.4 mm counts are dominated by\nsynchroton-dominated sources above ~15 mJy and by dust-dominated sources below\nthat flux level. We detect 141 synchrotron-dominated sources and 47\ndust-dominated sources at S/N > 4.5 in at least one band. All of the most\nsignificantly detected members of the synchrotron-dominated population are\nassociated with sources in previously published radio catalogs. Some of the\ndust-dominated sources are associated with nearby (z << 1) galaxies whose dust\nemission is also detected by the Infrared Astronomy Satellite (IRAS). However,\nmost of the bright, dust-dominated sources have no counterparts in any existing\ncatalogs. We argue that these sources represent the rarest and brightest\nmembers of the population commonly referred to as sub-millimeter galaxies\n(SMGs). Because these sources are selected at longer wavelengths than in\ntypical SMG surveys, they are expected to have a higher mean redshift\ndistribution and may provide a new window on galaxy formation in the early\nuniverse.