Chen, Chian-Chou and Smail, Ian and Swinbank, A. M. and Simpson, J. M. and Ma, Cheng-Jiun and Alexander, D. M. and Biggs, A. D. and Brandt, W. N. and Chapman, S. C. and Coppin, K. E. K. and Danielson, A. L. R. and Dannerbauer, H. and Edge, A. C. and Greve, T. R. and Ivison, R. J. and Karim, A. and Menten, Karl M. and Schinnerer, E. and Walter, F. and Wardlow, J. L. and Weiß, A. and van der Werf, P. P. (2015) An ALMA Survey of Submillimeter Galaxies in the Extended Chandra Deep Field South : Near-infrared Morphologies and Stellar Sizes. The Astrophysical Journal, 799 (2). p. 194. ISSN 0004-637X
Abstract
We analyze Hubble Space Telescope WFC3/H 160-band observations of a sample of 48 Atacama Large Millimeter/submillimeter Array detected submillimeter galaxies (SMGs) in the Extended Chandra Deep Field South field, to study their stellar morphologies and sizes. We detect 79% ± 17% of the SMGs in the H 160-band imaging with a median sensitivity of 27.8 mag, and most (80%) of the nondetections are SMGs with 870 μm fluxes of S 870 <3 mJy. With a surface brightness limit of μ H ~ 26 mag arcsec-2, we find that 82% ± 9% of the H 160-band-detected SMGs at z = 1-3 appear to have disturbed morphologies, meaning they are visually classified as either irregulars or interacting systems, or both. By determining a Sérsic fit to the H 160 surface brightness profiles, we derive a median Sérsic index of n = 1.2 ± 0.3 and a median half-light radius of re = 4.4+1.1-0.5 kpc for our SMGs at z = 1-3. We also find significant displacements between the positions of the H 160 component and 870 μm emission in these systems, suggesting that the dusty starburst regions and less-obscured stellar distribution are not colocated. We find significant differences in the sizes and the Sérsic index between our z = 2-3 SMGs and z ~ 2 quiescent galaxies, suggesting that a major transformation of the stellar light profile is needed in the quenching processes if SMGs are progenitors of the red-and-dead z ~ 2 galaxies. Given the short-lived nature of SMGs, we postulate that the majority of the z = 2-3 SMGs with S 870 gsim 2 mJy are early/mid-stage major mergers.