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Author
Vizgan, D.Greve, T.R.
Olsen, K.P.
Zanella, A.
Narayanan, D.
Davè, R.
Magdis, G.E.
Popping, G.
Valentino, F.
Heintz, K.E.
Affiliation
Department of Astronomy and Steward Observatory, University of ArizonaIssue Date
2022
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IOP Publishing LtdCitation
Vizgan, D., Greve, T. R., Olsen, K. P., Zanella, A., Narayanan, D., Davè, R., Magdis, G. E., Popping, G., Valentino, F., & Heintz, K. E. (2022). Tracing Molecular Gas Mass in z ≃ 6 Galaxies with [C ii]. Astrophysical Journal, 929(1).Journal
Astrophysical JournalRights
Copyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.Collection Information
This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at repository@u.library.arizona.edu.Abstract
We investigate the fine-structure [C ii] line at 158 μm as a molecular gas tracer by analyzing the relationship between molecular gas mass (M mol) and [C ii] line luminosity (L [C II]) in 11,125 z ≃ 6 star-forming, main-sequence galaxies from the simba simulations, with line emission modeled by the Simulator of Galaxy Millimeter/Submillimeter Emission. Though most (∼ 50%-100%) of the gas mass in our simulations is ionized, the bulk (>50%) of the [C ii] emission comes from the molecular phase. We find a sublinear (slope 0.78 ± 0.01) logL[CII]-logMmol relation, in contrast with the linear relation derived from observational samples of more massive, metal-rich galaxies at z ≲2 6. We derive a median [C ii]-to-M mol conversion factor of α [C II] ≃ 18 M ⊙ /L⊙ . This is lower than the average value of ≃30 M ⊙ /L ⊙ derived from observations, which we attribute to lower gas-phase metallicities in our simulations. Thus, a lower, luminosity-dependent conversion factor must be applied when inferring molecular gas masses from [C ii] observations of low-mass galaxies. For our simulations, [C ii] is a better tracer of the molecular gas than CO J = 1-0, especially at the lowest metallicities, where much of the gas is CO-dark. We find that L [C II] is more tightly correlated with M mol than with star formation rate (SFR), and both the logL[CII]-logMmol and logL[CII]-logSFR relations arise from the Kennicutt-Schmidt relation. Our findings suggest that L [C II] is a promising tracer of the molecular gas at the earliest cosmic epochs. © 2022. The Author(s). Published by the American Astronomical Society.Note
Open access journalISSN
0004-637XVersion
Final published versionae974a485f413a2113503eed53cd6c53
10.3847/1538-4357/ac5cba
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Except where otherwise noted, this item's license is described as Copyright © 2022. The Author(s). Published by the American Astronomical Society. Original content from this work may be used under the terms of the Creative Commons Attribution 4.0 licence.