Vz-GAL: Probing Cold Molecular Gas in Dusty Star-forming Galaxies at z=1-6
Journal article, 2026
We present the first results of Vz-GAL, a high-redshift CO(J = 1-0) large survey with the Karl G. Jansky Very Large Array, targeting 92 Herschel-selected, infrared-luminous, dusty star-forming galaxies at redshifts 1-6. These sources are selected based on having redshifts and mid-/high-J CO transitions from the NOrthern Extended Millimeter Array z-GAL survey. We successfully detect CO(J = 1-0) emission in 90/92 galaxies at the expected positions and redshifts, including nine tentative detections at 2 sigma-3 sigma significance, and CO(J = 2-1) emission in 10 of these galaxies. The CO(J = 1-0) luminosities suggest apparent gas masses in the range mu MH2 = (2-20) x 1011 (alpha CO/4.0) M circle dot, which implies gas depletion times of 50-600 Myr. These timescales show similar spread as local ULIRGs, suggesting a self-regulatory mechanism that maintains a consistent star formation rate per unit gas mass in starbursts across redshifts. To quantify the contribution of "excitation correction" factors to gas mass estimates, we calculate median CO line brightness temperature ratios of r21 = 0.88 +/- 0.25, r31 = 0.61 +/- 0.22, r41 = 0.49 +/- 0.15, r51 = 0.47 +/- 0.13, and r61 = 0.28 +/- 0.13. Accounting for these corrections results in a reduced scatter in "gas mass-star formation rate" relations. We also find a median log( L '[CI](3P1-3P0)/L ' CO(J=1-0))=-0.71 +/- 0.12 for a subsample of 23 sources, consistent with the ratios derived for local star-forming galaxies. Together, our findings are in agreement with common conditions in the cold gas reservoirs among star-forming galaxies over a broad range in star formation modes, efficiencies, and scales.
Author
Prachi Prajapati
Max Planck Society
University of Cologne
Dominik Riechers
University of Cologne
Pierre Cox
Pierre and Marie Curie University (UPMC)
Centre national de la recherche scientifique (CNRS)
Axel Weiss
Max Planck Society
Amelie Saintonge
Max Planck Society
Bethany Jones
University of Cologne
Tom Bakx
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Stefano Berta
Institut de Radioastronomie Millimétrique (IRAM)
Roberto Neri
Institut de Radioastronomie Millimétrique (IRAM)
Kirsty M. Butler
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Asantha Cooray
University of California
Diana Ismail
University of Strasbourg
Andrew J. Baker
University of the Western Cape
Rutgers University
Andrew Harris
University of Maryland
Rob Ivison
University of Edinburgh
Dublin Institute for Advanced Studies
Matthew Lehnert
Université de Lyon
Centre national de la recherche scientifique (CNRS)
Pierre and Marie Curie University (UPMC)
Lucia Marchetti
University of Cape Town
Istituto nazionale di astrofisica (INAF)
Hugo Messias
Atacama Large Millimeter-submillimeter Array (ALMA)
European Southern Observatory Santiago
Alain Omont
Pierre and Marie Curie University (UPMC)
Centre national de la recherche scientifique (CNRS)
Catherine Vlahakis
National Radio Astronomy Observatory
Chentao Yang
Chalmers, Space, Earth and Environment, Astronomy and Plasmaphysics
Astrophysical Journal, Supplement Series
0067-0049 (ISSN) 1538-4365 (eISSN)
Vol. 282 2 40Subject Categories (SSIF 2025)
Other Physics Topics
Astronomy, Astrophysics, and Cosmology
DOI
10.3847/1538-4365/ae27d4