Article Dans Une Revue The Astrophysical Journal Année : 2019

The ALMA Spectroscopic Survey in the HUDF: CO Luminosity Functions and the Molecular Gas Content of Galaxies through Cosmic History

Jorge Gónzalez-López
Manuel Aravena
Leindert Boogaard
Pierre Cox
Gergö Popping
Dominik Riechers
Bade Uzgil
Axel Weiss
Roberto J Assef
  • Fonction : Auteur
Franz Erik Bauer
  • Fonction : Auteur
Frank Bertoldi
Rychard Bouwens
Paulo C Cortes
  • Fonction : Auteur
Tanio Díaz-Santos
David Elbaz
Hanae Inami
Jacqueline Hodge
Rob Ivison
Benjamin Magnelli
Mladen Novak
Pascal Oesch
Hans-Walter Rix
Ian Smail
A. Mark Mark Swinbank
  • Fonction : Auteur
Rachel S Somerville
  • Fonction : Auteur
Paul van Der Werf
Jeff Wagg
  • Fonction : Auteur
Lutz Wisotzki
  • Fonction : Auteur

Résumé

We use the results from the ALMA large program ASPECS, the spectroscopic survey in the Hubble Ultra Deep Field (HUDF), to constrain CO luminosity functions of galaxies and the resulting redshift evolution of ρ(H 2). The broad frequency range covered enables us to identify CO emission lines of different rotational transitions in the HUDF at z>1. We find strong evidence that the CO luminosity function evolves with redshift, with the knee of the CO luminosity function decreasing in luminosity by an order of magnitude from ∼2 to the local universe. Based on Schechter fits, we estimate that our observations recover the majority (up to ∼90%, depending on the assumptions on the faint end) of the total cosmic CO luminosity at z=1.0-3.1. After correcting for CO excitation, and adopting a Galactic CO-to-H 2 conversion factor, we constrain the evolution of the cosmic molecular gas density ρ(H 2): this cosmic gas density peaks at z∼1.5 and drops by a factor of-+ 6.5 1.4 1.8 to the value measured locally. The observed evolution in ρ(H 2), therefore, closely matches the evolution of the cosmic star formation rate density ρ SFR. We verify the robustness of our result with respect to assumptions on source inclusion and/or CO excitation. As the cosmic star formation history can be expressed as the product of the star formation efficiency and the cosmic density of molecular gas, the similar evolution of ρ(H 2) and ρ SFR leaves only little room for a significant evolution of the average star formation efficiency in galaxies since z∼3 (85% of cosmic history).

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hal-02325055 , version 1 (22-10-2019)

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Roberto Decarli, Fabian Walter, Jorge Gónzalez-López, Manuel Aravena, Leindert Boogaard, et al.. The ALMA Spectroscopic Survey in the HUDF: CO Luminosity Functions and the Molecular Gas Content of Galaxies through Cosmic History. The Astrophysical Journal, 2019, 882 (2), pp.138. ⟨10.3847/1538-4357/ab30fe⟩. ⟨hal-02325055⟩
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