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The [C II] emission as a molecular gas mass tracer in galaxies at low and high redshift

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Version 2 2023-06-12, 07:31
Version 1 2023-06-09, 16:04
journal contribution
posted on 2023-06-12, 07:31 authored by A Zanella, E Daddi, G Magdis, T Diaz Santos, D Cormier, D Liu, A Cibinel, R Gobat, M Dickinson, Mark Sargent, G Popping, S C Madden, M Bethermin, T M Hughes, F Valentino, W Rujopakarn, M Pannella, F Bournaud, F Walter, T Wang, D Elbaz, Rosemary Coogan
We present ALMA Band 9 observations of the [C II]158um emission for a sample of 10 main-sequence galaxies at redshift z ~ 2, with typical stellar masses (log M*/Msun ~ 10.0 - 10.9) and star formation rates (~ 35 - 115 Msun/yr). Given the strong and well understood evolution of the interstellar medium from the present to z = 2, we investigate the behaviour of the [C II] emission and empirically identify its primary driver. We detect [C II] from six galaxies (four secure, two tentative) and estimate ensemble averages including non detections. The [C II]-to-infrared luminosity ratio (L[C II]/LIR) of our sample is similar to that of local main-sequence galaxies (~ 2 x 10^-3), and ~ 10 times higher than that of starbursts. The [C II] emission has an average spatial extent of 4 - 7 kpc, consistent with the optical size. Complementing our sample with literature data, we find that the [C II] luminosity correlates with galaxies' molecular gas mass, with a mean absolute deviation of 0.2 dex and without evident systematics: the [C II]-to-H2 conversion factor (alpha_[C II] ~ 30 Msun/Lsun) is largely independent of galaxies' depletion time, metallicity, and redshift. [C II] seems therefore a convenient tracer to estimate galaxies' molecular gas content regardless of their starburst or main-sequence nature, and extending to metal-poor galaxies at low and high redshifts. The dearth of [C II] emission reported for z > 6 - 7 galaxies might suggest either a high star formation efficiency or a small fraction of UV light from star formation reprocessed by dust.

History

Publication status

  • Published

File Version

  • Published version

Journal

Monthly Notices of the Royal Astronomical Society

ISSN

0035-8711

Publisher

Oxford University Press

Issue

2

Volume

481

Page range

1976-1999

Department affiliated with

  • Physics and Astronomy Publications

Research groups affiliated with

  • Astronomy Centre Publications

Full text available

  • Yes

Peer reviewed?

  • Yes

Legacy Posted Date

2018-11-28

First Open Access (FOA) Date

2018-11-28

First Compliant Deposit (FCD) Date

2018-11-27

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