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

• Published in: The Astrophysical journal Vol. 945; no. 1; pp. 24 - 42
• Main Authors: 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.
• Format: Journal Article
• Language: English
• Published: Philadelphia The American Astronomical Society 01.03.2023; IOP Publishing; American Astronomical Society
• Subjects: Active galactic nuclei; Angular resolution; Astrophysics; CO line emission; Cosmology and Extra-Galactic Astrophysics; Depletion; Galaxies; High-redshift galaxies; Infrared stars; Line spectra; Molecular gases; Radiation; Radiative transfer; Radio emission; Sciences of the Universe; Star & galaxy formation; Star formation; Starburst galaxies; Stars; Stars & galaxies; Synchrotron radiation; Synchrotrons
• ISSN: 0004-637X; 1538-4357; 1538-4357
• DOI: 10.3847/1538-4357/acb6f7

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 12 CO(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 pc 2 , 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.