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

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

*Corresponding author for this work

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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 1011 K km s−1 pc2, and molecular gas masses of (µ)MH2 =1.3–8.6x1011 Me, where (μ) is the magnification factor. The derived molecular gas depletion times of tdep = 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 r32/10 = 0.4–1.4, r43/10 = 0.4–1.7, and r54/10 = 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 nH2 = 0.3 - 8.5 x103 cm−3 and temperatures of TK = 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.
Original languageEnglish
Article number24
JournalAstrophysical Journal
Issue number1
Number of pages19
Publication statusPublished - 2023


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