An, F.X.Birkin, J.EWeiss, A2021-05-172021-05-172021An, F.X. et al. (2021). An ALMA/NOEMA survey of the molecular gas properties of high-redshift star-forming galaxies. Monthly Notices of the Royal Astronomical Society, 501(3), 3926-39500035-871110.1093/mnras/staa3862http://hdl.handle.net/10566/6162We have used ALMA and NOEMA to study the molecular gas reservoirs in 61 ALMA-identified submillimetre galaxies (SMGs) in the COSMOS, UDS, and ECDFS fields. We detect 12CO (Jup = 2-5) emission lines in 50 sources, and [C I](3P1 -3P0) emission in eight, at z = 1.2-4.8 and with a median redshift of 2.9±0.2. By supplementing our data with literature sources, we construct a statistical CO spectral line energy distribution and find that the 12CO line luminosities in SMGs peak at Jup ∼ 6, consistent with similar studies. We also test the correlations of the CO, [C I], and dust as tracers of the gas mass, finding the three to correlate well, although the CO and dust mass as estimated from the 3-mm continuum are preferable. We estimate that SMGs lie mostly on or just above the star-forming main sequence, with a median gas depletion timescale, tdep = Mgas/SFR, of 210±40 Myr for our sample.enGalaxies: evolutionGalaxies: Star formationSubmillimetre: galaxiesArticle