A NOEMA molecular line scan of the Hubble Deep Field North: Improved constraints on the CO luminosity functions and cosmic density of molecular gas

Understand

We present measurements of the CO luminosity functions (LFs) and the evolution of the cosmic molecular gas density out to z~6 based on an 8.5 arcmin^2 spectral scan survey at 3mm of the iconic Hubble Deep Field North (HDF-N) observed with the NOrthern Extended Millimeter Array (NOEMA).

• We use matched filtering to search for line emission from galaxies and determine their redshift probability distributions exploiting the extensive multi-wavelength data for the HDF-N.
• We identify the 7 highest-fidelity sources as CO emitters at 1<z<6, including the well-known submillimeter galaxy HDF850.1 at z=5.18.
• Four high-fidelity 3mm continuum sources are all found to be radio galaxies at z<=1, plus HDF850.1.