Revisited Cold Gas Content with Atomic Carbon [Ci] in z = 2.5 Protocluster Galaxies

Minju M. Lee, Ichi Tanaka, Daisuke Iono, Ryohei Kawabe, Tadayuki Kodama, Kotaro Kohno, Toshiki Saito, Yoichi Tamura

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4 Citations (Scopus)


We revisit the cold gas contents of galaxies in a protocluster at z = 2.49 using the lowest neutral atomic carbon transition [C i] 3 P 1 - 3 P 0 from Atacama Large Millimeter/submillimeter Array observations. We aim to test if the same gas-mass calibration adopted in field galaxies can be applied to protocluster galaxies. Five galaxies out of 16 targeted galaxies are detected in the [C i] line, and these are all previously detected in CO (3-2) and CO (4-3) and three in 1.1 mm dust continuum. We investigate the line luminosity relations between CO and [C i] in the protocluster and compare with other previous studies. We then compare the gas mass based on three gas tracers of [C i], CO(3-2), and dust if at least one of the last two tracers are available. Using the calibration adopted for field main-sequence galaxies, the [C i]-based gas measurements are lower than or comparable to the CO-based gas measurements by -0.35 dex at the lowest with the mean deviation of -0.14 dex. The differences between [C i]- and the dust- based measurements are relatively mild by up to 0.16 dex with the mean difference of 0.02 dex. Taking these all together with calibration uncertainties, with the [C i] line, we reconfirm our previous findings that the mean gas fraction is comparable to field galaxies for a stellar-mass range of . However, at least for these secure five detections, the depletion timescale decreases more rapidly with stellar mass than field galaxies that might be related to earlier quenching in dense environments.

Original languageEnglish
Article number181
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 2021 Mar 10

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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