Optical and near-IR properties of submillimetre galaxies in the GOODS-North field

1. Optical and near-IR properties of submillimetre galaxies in the GOODS-North field Alexandra Pope, D. Scott (UBC), C. Borys, C. Conselice (Caltech), M. Dickinson (NOAO), B. Mobasher (STScI) Figure 1: JCMT SCUBA 850m S/N map 42 sources Integration time~1300 ksec Figure 2: HST ACS bviz colour image 32 000 sources Integration time~500 ksec ABSTRACT We present a new sub-mm 'Super-map' in the GOODS-North field containing 42 statistically robust sources at 850 m. This map contains new data, and several new sources (including the brightest one in the survey). We have used the ACS HST images and ground-based near-IR observations from GOODS to study these sources. With the depth achieved by this survey, optical counterparts have been found for all the radio-detected sub-mm sources. We have used the colours, morphologies and photometric redshifts of these secure identifications to help identify counterparts to the radio-undetected sources, finding that certain combinations of optical properties can be used to successfully identify the counterpart to a sub-mm source. 75% of our sources have a unique optical counterpart using our new techniques for counterpart identification, and an additional ~15% have more than one possibility that meet our criteria in the ACS images. Thus only ~10% of our sources lack a plausible counterpart, meaning that we have the first sample of SCUBA sources which is nearly completely identified. We have found a higher ERO rate than other sub-mm surveys, due to the increased depth in the optical images. The median redshift from optical photometric redshifts for the bright radio-detected sources is around 2, and rises to ~2.6 for the bright radio-undetected sources. While the quantitative morphologies span a range of values, in general the sub-mm galaxies show larger sizes and a higher degree of asymmetry than other galaxy populations at the same redshifts. With the current and upcoming GOODS-North data from Spitzer, we will be able test our counterpart selection techniques and use the additional IR photometric points to study the optical/IR SEDs of an sample of sub-mm galaxies. Redshifts Colours Morphologies Figure 4: Near-IR colour-colour plot. Dusty EROs with 1<z<2 should lie in top-right corner. Figure 3: Photometric redshift distribution. Figure 5: Size at all redshifts. References: Borys et al. 2003, MNRAS, 344, 385; Borys et al. 2004, MNRAS, in press, (astro-ph/0408376); Chapman et al. 2003, Nature, 422, 695; Conselice 2003, ApJSS, 147, 1; Giavalisco et al. 2004, ApJ, 600, 93; Mobasher et al. 2004, ApJ, 600,167; Pope et al. 2004, in prep.; Pozzetti & Mannucci, 2000, MNRAS, 317, 1