Research Repository

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

## Authors

F. Stanley

B. M. Jones

D. A. Riechers

C. Yang

S. Berta

P. Cox

T. J. L. C. Bakx

A. Cooray

H. Dannerbauer

SIMON DYE Simon.Dye@nottingham.ac.uk
Associate Professor

D. H. Hughes

R. J. Ivison

S. Jin

M. Lehnert

R. Neri

A. Omont

P. van der Werf

A. Weiss

### 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 $(\mu ){L}_{\mathrm{CO}(1-0)}^{{\prime} }=0.4\mbox{--}2.9\times {10}^{11}$ K km s−1 pc2, and molecular gas masses of $(\mu ){M}_{{{\rm{H}}}_{2}}\,=1.3\mbox{--}8.6\times {10}^{11}$ M⊙, 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 ${n}_{{{\rm{H}}}_{2}}=0.3-8.5\times {10}^{3}$ 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.

### 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 Jan 27, 2023 Mar 2, 2023 Mar 1, 2023 Mar 4, 2023 Mar 6, 2023 Astrophysical Journal 0004-637X 1538-4357 American Astronomical Society Peer Reviewed 945 1 24 https://doi.org/10.3847/1538-4357/acb6f7 High-redshift galaxies; Galaxies; Starburst galaxies; CO line emission https://nottingham-repository.worktribe.com/output/17947634 https://iopscience.iop.org/article/10.3847/1538-4357/acb6f7