VLA Legacy Survey of Molecular Gas in Massive Star-forming Galaxies at High Redshift

Castillo, Marta Frias; Hodge, Jacqueline; Rybak, Matus; van der Werf, Paul; Smail, Ian; Birkin, Jack E.; Chen, Chian-Chou; Chapman, Scott C.; Hill, Ryley; del P.Lagos, Claudia; Liao, Cheng-Lin; da Cunha, Elisabete; Rivera, Gabriela Calistro; Chen, Jianhang; Jiménez-Andrade, E.F.; Murphy, Eric J.; Scott, Douglas; Swinbank, A.M.; Walter, Fabian; Ivison, R.J.; Dannerbauer, Helmut

Abstract

We present the initial results of an ongoing survey with the Karl G. Jansky Very Large Array targeting the CO(J = 1–0) transition in a sample of 30 submillimeter-selected, dusty star-forming galaxies (SFGs) at z = 2–5 with existing mid-J CO detections from the Atacama Large Millimeter/submillimeter Array and NOrthern Extended Millimeter Array, of which 17 have been fully observed. We detect CO(1–0) emission in 11 targets, along with three tentative (∼1.5σ–2σ) detections; three galaxies are undetected. Our results yield total molecular gas masses of 6–23 × 1010 (αCO/1) Me, with gas mass fractions, fgas = Mmol/(M*+Mmol), of 0.1–0.8 and a median depletion time of (140 ± 70) Myr. We find median CO excitation ratios of r31 = 0.75 ± 0.39 and r41 = 0.63 ± 0.44, with significant scatter. We find no significant correlation between the excitation ratio and a number of key parameters such as redshift, CO(1–0) line width, or ΣSFR. We only find a tentative positive correlation between r41 and the star-forming efficiency, but we are limited by our small sample size. Finally, we compare our results to predictions from the SHARK semi-analytical model, finding a good agreement between the molecular gas masses, depletion times, and gas fractions of our sources and their SHARK counterparts. Our results highlight the heterogeneous nature of the most massive SFGs at high redshift, and the importance of CO(1–0) observations to robustly constrain their total molecular gas content and interstellar medium properties.

Citation

Castillo, M. F., Hodge, J., Rybak, M., van der Werf, P., Smail, I., Birkin, J. E., …Dannerbauer, H. (2023). VLA Legacy Survey of Molecular Gas in Massive Star-forming Galaxies at High Redshift. Astrophysical Journal, 945(2), Article 128. https://doi.org/10.3847/1538-4357/acb931

• Journal Article Type: Article
• Acceptance Date: Feb 1, 2023
• Online Publication Date: Mar 14, 2023
• Publication Date: Mar 10, 2023
• Deposit Date: Jun 12, 2023
• Publicly Available Date: Jun 12, 2023
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 945
• Issue: 2
• Article Number: 128
• DOI: https://doi.org/10.3847/1538-4357/acb931