The ALPINE-ALMA [C II] survey. Molecular gas budget in the early Universe as traced by [C II] - Archive ouverte HAL Access content directly
Journal Articles Astronomy and Astrophysics - A&A Year : 2020

The ALPINE-ALMA [C II] survey. Molecular gas budget in the early Universe as traced by [C II]

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M. Dessauges-Zavadsky
  • Function : Author
M. Ginolfi
  • Function : Author
F. Pozzi
  • Function : Author
M. Béthermin
S. Fujimoto
  • Function : Author
J. D. Silverman
  • Function : Author
G. C. Jones
  • Function : Author
L. Vallini
  • Function : Author
D. Schaerer
  • Function : Author
A. L. Faisst
  • Function : Author
Y. Fudamoto
  • Function : Author
P. Cassata
  • Function : Author
F. Loiacono
  • Function : Author
P. L. Capak
  • Function : Author
L. Yan
  • Function : Author
R. Amorin
  • Function : Author
S. Bardelli
M. Boquien
A. Cimatti
C. Gruppioni
  • Function : Author
N. P. Hathi
  • Function : Author
E. Ibar
  • Function : Author
A. M. Koekemoer
  • Function : Author
B. C. Lemaux
D. Narayanan
  • Function : Author
P. A. Oesch
  • Function : Author
G. Rodighiero
  • Function : Author
M. Romano
  • Function : Author
M. Talia
  • Function : Author
S. Toft
  • Function : Author
D. Vergani
  • Function : Author
G. Zamorani
E. Zucca

Abstract

The molecular gas content of normal galaxies at z > 4 is poorly constrained because the commonly used molecular gas tracers become hard to detect at these high redshifts. We use the [C II] 158 μm luminosity, which was recently proposed as a molecular gas tracer, to estimate the molecular gas content in a large sample of main sequence star-forming galaxies at z = 4.4 - 5.9, with a median stellar mass of 109.7 M, drawn from the ALMA Large Program to INvestigate [C II] at Early times survey. The agreement between the molecular gas masses derived from [C II] luminosities, dynamical masses, and rest-frame 850 μm luminosities extrapolated from the rest-frame 158 μm continuum supports [C II] as a reliable tracer of molecular gas in our sample. We find a continuous decline of the molecular gas depletion timescale from z = 0 to z = 5.9, which reaches a mean value of (4.6 ± 0.8) × 108 yr at z ∼ 5.5, only a factor of between two and three shorter than in present-day galaxies. This suggests a mild enhancement of the star formation efficiency toward high redshifts. Our estimates also show that the previously reported rise in the molecular gas fraction flattens off above z ∼ 3.7 to achieve a mean value of 63%±3% over z = 4.4 - 5.9. This redshift evolution of the gas fraction is in line with that of the specific star formation rate. We use multi-epoch abundance-matching to follow the gas fraction evolution across cosmic time of progenitors of z = 0 Milky Way-like galaxies in ∼1013 M halos and of more massive z = 0 galaxies in ∼1014 M halos. Interestingly, the former progenitors show a monotonic increase of the gas fraction with redshift, while the latter show a steep rise from z = 0 to z ∼ 2 followed by a constant gas fraction from z ∼ 2 to z = 5.9. We discuss three possible effects, namely outflows, a pause in gas supply, and over-efficient star formation, which may jointly contribute to the gas fraction plateau of the latter massive galaxies.
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Dates and versions

insu-03667047 , version 1 (13-05-2022)

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M. Dessauges-Zavadsky, M. Ginolfi, F. Pozzi, M. Béthermin, O. Le Fèvre, et al.. The ALPINE-ALMA [C II] survey. Molecular gas budget in the early Universe as traced by [C II]. Astronomy and Astrophysics - A&A, 2020, 643, ⟨10.1051/0004-6361/202038231⟩. ⟨insu-03667047⟩
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