An ALMA/NOEMA survey of the molecular gas properties of high-redshift star-forming galaxies
Journal article, 2021
We 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. Additionally, tdep declines with redshift across z ∼ 1-5, while the molecular gas fraction, μgas = Mgas/M*, increases across the same redshift range. Finally, we demonstrate that the distribution of total baryonic mass and dynamical line width, Mbaryon-σ, for our SMGs is consistent with that followed by early-type galaxies in the Coma cluster, providing strong support to the suggestion that SMGs are progenitors of massive local spheroidal galaxies. On the basis of this, we suggest that the SMG populations above and below an 870-μm flux limit of S870 ∼ 5mJy may correspond to the division between slow and fast rotators seen in local early-type galaxies.
galaxies: Star formation
submillimetre: Galaxies
galaxies: Evolution
Author
Jack E. Birkin
Durham University
Axel Weiss
Max Planck Society
J. L. Wardlow
Lancaster University
Ian Smail
Durham University
A. M. Swinbank
Durham University
U. Dudzeviciute
Durham University
Fang Xia An
University of the Western Cape
Y. Ao
University of Science and Technology of China
Chinese Academy of Sciences
S. C. Chapman
Dalhousie University
Chian Chou Chen
Academia Sinica
E. da Cunha
University of Western Australia
H. Dannerbauer
Instituto de Astrofísica de Canarias
University of La Laguna
Bitten Gullberg
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
J. A. Hodge
Leiden University
S. Ikarashi
Durham University
R. J. Ivison
European Southern Observatory (ESO)
Y. Matsuda
The Graduate University for Advanced Studies (SOKENDAI)
National Astronomical Observatory of Japan
S. M. Stach
Durham University
F. Walter
Max Planck Society
W. H. Wang
Academia Sinica
P. van der Werf
Leiden University
Monthly Notices of the Royal Astronomical Society
0035-8711 (ISSN) 1365-2966 (eISSN)
Vol. 501 3 3926-3950Subject Categories
Subatomic Physics
Astronomy, Astrophysics and Cosmology
Probability Theory and Statistics
DOI
10.1093/mnras/staa3862