The ALMA Spectroscopic Survey in the Hubble Ultra Deep Field: Multiband Constraints on Line-luminosity Functions and the Cosmic Density of Molecular Gas

We present a CO and atomic fine-structure line-luminosity function analysis using the ALMA Spectroscopic Survey (ASPECS) in the Hubble Ultra Deep Field. ASPECS consists of two spatially overlapping mosaics that cover the entire ALMA 3 mm and 1.2 mm bands. We combine the results of a line-candidate search of the 1.2 mm data cube with those previously obtained from the 3 mm cube. Our analysis shows that ~80% of the line flux observed at 3 mm arises from CO(2–1) or CO(3–2) emitters at z = 1–3 ("cosmic noon"). At 1.2 mm, more than half of the line flux arises from intermediate-J CO transitions (J_(up) = 3–6); ~12% from neutral carbon lines; and