Resolved CO(1–0) Emission and Gas Properties in Luminous Dusty Star-forming Galaxies at z = 2–4

Stanley, F.; Jones, B. M.; Riechers, D. A.; Yang, C.; Berta, S.; Cox, P.; Bakx, T. J.L.C.; Cooray, A.; Dannerbauer, H.; Dye, S.; Hughes, D. H.; Ivison, R. J.; Jin, S.; Lehnert, M.; Neri, R.; Omont, A.; van der Werf, P.; Weiss, A.

Abstract

We present the results of a survey of CO(1−0) emission in 14 infrared luminous dusty star-forming galaxies (DSFGs) at 2 < z < 4 with the NSF’s Karl G. Jansky Very Large Array. All sources are detected in 12CO(1−0), with an angular resolution of ∼1″. Seven sources show extended and complex structure. We measure CO luminosities of ( μ ) L CO ( 1 − 0 ) ′ = 0.4 - 2.9 × 10 11 K km s−1 pc2, and molecular gas masses of ( μ ) M H 2 = 1.3 - 8.6 × 10 11 M ⊙, where (μ) is the magnification factor. The derived molecular gas depletion times of t dep = 40-460 Myr, cover the expected range of both normal star-forming galaxies and starbursts. Compared to the higher −J CO transitions previously observed for the same sources, we find CO temperature brightness ratios of r 32/10 = 0.4-1.4, r 43/10 = 0.4-1.7, and r 54/10 = 0.3-1.3. We find a wide range of CO spectral line energy distributions (SLEDs), in agreement with other high-z DSFGs, with the exception of three sources that are most comparable to Cloverleaf and APM08279+5255. Based on radiative transfer modeling of the CO SLEDs we determine densities of n H 2 = 0.3 − 8.5 × 10 3 cm−3 and temperatures of T K = 100-200 K. Lastly, four sources are detected in the continuum, three have radio emission consistent with their infrared-derived star formation rates, while HerBS-70E requires an additional synchrotron radiation component from an active galactic nucleus. Overall, we find that even though the sample is similarly luminous in the infrared, by tracing the CO(1−0) emission a diversity of galaxy and excitation properties are revealed, demonstrating the importance of CO(1−0) observations in combination to higher-J transitions.

Citation

Stanley, F., Jones, B. M., Riechers, D. A., Yang, C., Berta, S., Cox, P., …Weiss, A. (2023). Resolved CO(1–0) Emission and Gas Properties in Luminous Dusty Star-forming Galaxies at z = 2–4. Astrophysical Journal, 945(1), Article 24. https://doi.org/10.3847/1538-4357/acb6f7

• Journal Article Type: Article
• Acceptance Date: Jan 27, 2023
• Online Publication Date: Mar 2, 2023
• Publication Date: Mar 1, 2023
• Deposit Date: Mar 4, 2023
• Publicly Available Date: Mar 6, 2023
• Journal: Astrophysical Journal
• Print ISSN: 0004-637X
• Electronic ISSN: 1538-4357
• Publisher: American Astronomical Society
• Peer Reviewed: Peer Reviewed
• Volume: 945
• Issue: 1
• Article Number: 24
• DOI: https://doi.org/10.3847/1538-4357/acb6f7
• Keywords: High-redshift galaxies; Galaxies; Starburst galaxies; CO line emission
• Public URL: https://nottingham-repository.worktribe.com/output/17947634
• Publisher URL: https://iopscience.iop.org/article/10.3847/1538-4357/acb6f7