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., Bakx, T. J., 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. (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