An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South: Spectroscopic Redshifts

Abstract

We present spectroscopic redshifts of S-870 (mu m) greater than or similar to 2 mJy submillimeter galaxies (SMGs),. which have been identified from the ALMA follow-up observations of 870 mu m. detected sources in the Extended Chandra Deep Field South (the ALMA-LESS survey). We derive spectroscopic redshifts for 52 SMGs, with a median of z = 2.4 +/- 0.1. However, the distribution features a high-redshift tail, with similar to 23% of the SMGs at z >= 3. Spectral diagnostics suggest that the SMGs are young starbursts, and the velocity offsets between the nebular emission and UV ISM absorption lines suggest that many are driving winds, with velocity offsets of up to 2000 km s(-1). Using the spectroscopic redshifts and the extensive UV-to-radio photometry in this field, we produce optimized spectral energy distributions (SEDs) using MAGPHYS, and use the SEDs to infer a median stellar mass of M star = (6 +/- 1) x 10(10) M circle dot for our SMGs with spectroscopic redshift. By combining these stellar masses with the star formation rates (measured from the far-infrared SEDs), we show that SMGs (on average) lie a factor of similar to 5 above the so-called "main sequence" at z similar to 2. We provide this library of 52 template fits with robust and uniquely well-sampled SEDs as a resource for future studies of SMGs, and also release the spectroscopic catalog of similar to 2000 (mostly infrared-selected) galaxies targeted as part of the spectroscopic campaign.