A NOEMA Molecular Line Scan of the Hubble Deep Field North: Improved Constraints on the CO Luminosity Functions and Cosmic Density of Molecular Gas

We present measurements of the CO luminosity functions (LFs) and evolution cosmic molecular gas density out to z~6 based on an 8.5 arcmin^2 spectral scan survey at 3mm iconic Hubble Deep Field North (HDF-N) observed with NOrthern Extended Millimeter Array (NOEMA). use matched filtering search for line emission from galaxies determine their redshift probability distributions exploiting extensive multi-wavelength data HDF-N. identify 7 highest-fidelity sources as emitters 1=5.0. The relatively large area depth NOEMA extends existing 1<z<4 above knee, yielding somewhat lower by 0.15-0.4 dex overlap region CO(2-1) CO(3-2) transitions, attributed variance. perform joint analysis Ultra ASPECS, finding that they can well described single Schechter function. is good agreement earlier determinations. This implies impact field-to-field variance consistent previous estimates, adding challenges simulations model principles.