Spatially Resolved [C ii] Emission in SPT0346-52: A Hyper-starburst Galaxy Merger at z ∼ 5.7

Abstract

SPT0346-52 is one of the most most luminous and intensely star-forming galaxies in the universe, with L-FIR > 10(13) L-circle dot and Sigma(SFR) approximate to 4200 M-circle dot yr(-1) kpc(-2). In this paper, we present similar to 0 ''(center dot)15 ALMA observations of the [C II] 158 mu m emission line in this z = 5.7 dusty star-forming galaxy. We use a pixellated lensing reconstruction code to spatially and kinematically resolve the source-plane [C II] and rest-frame 158 mu m dust continuum structure at similar to 700 pc (similar to 0 ''(center dot)12) resolution. We discuss the [C II] deficit with a pixellated study of the L-[C II]/L-FIR ratio in the source plane. We find that individual pixels within the galaxy follow the same trend found using unresolved observations of other galaxies, indicating that the deficit arises on scales less than or similar to 700 pc. The lensing reconstruction reveals two spatially and kinematically separated components (similar to 1 kpc and similar to 500 km s(-1) apart) connected by a bridge of gas. Both components are found to be globally unstable, with Toomre Q instability parameters << 1 everywhere. We argue that SPT0346-52 is undergoing a major merger, which is likely driving the intense and compact star formation.