Characterizing Spatially-Resolved Multi-Wavelength Emission from Sub-Millimeter Galaxies

Massive, dusty sub-millimeter galaxies (SMGs) near redshift 2 are some of the most extremely star-forming systems known, and may be the progenitors of modern elliptical galaxies. As a consequence of high levels of dust attenuation, rest-frame ultraviolet and optical light are largely obscured, and often present a highly biased view of the star formation within these systems. Recent studies of small samples of SMGs with HST and ALMA have reached sufficient angular resolution to quantify their spatially-resolved emission across the wavelength spectrum. In this paper, we perform a systematic study of the spatially-resolved, multi-wavelength emission from 48 SMGs, compared to a control sample of 6 times as many similarly massive, less FIR-luminous sources at the same redshift. We derive radial profiles, half-light radii, and flux-weighted centers for the SMGs and control sample, in five HST bands: F606W & F814W (which trace rest-frame ultraviolet emission at z = 2), and F125W, F140W, & F160W (which trace rest-frame optical emission). For many of the galaxies, half-light radius of rest-frame ultraviolet emission is larger than the half-light radius of rest-frame optical emission, potentially due to preferential dust attenuation near the center of the galaxies. This effect is more marked in SMGs than the control sample. We also see larger offsets between the flux-weighted centers of rest-frame ultraviolet and rest-frame optical light for the SMGs than for the control sample. The SAO REU program is funded in part by the National Science Foundation REU and Department of Defense ASSURE programs under NSF Grant no. AST-2050813, and by the Smithsonian Institution.