Sub-mm emission line deep fields: CO and [CII] luminosity functions out to z = 6

Gergö Popping, Eelco van Kampen, Roberto Decarli, Marco Spaans, Rachel S. Somerville, Scott C. Trager

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41 Scopus citations


Nowthat Atacama Large (Sub)Millimeter Array is reaching its full capabilities, observations of sub-mm emission line deep fields become feasible. We couple a semi-analytic model of galaxy formation with a radiative transfer code to make predictions for the luminosity function of CO J =1-0 out to CO J = 6-5 and [C II] at redshifts z= 0-6. We find that (1) our model correctly reproduces the CO and [C II] emission of low- and high-redshift galaxies and reproduces the available constraints on the CO luminosity function at z ≤ 2.75; (2) we find that the CO and [C II] luminosity functions of galaxies increase from z = 6 to z = 4, remain relatively constant till z = 1 and rapidly decrease towards z = 0. The galaxies that are brightest in CO and [C II] are found at z ~ 2; (3) the CO J = 3-2 emission line is most favourable to study the CO luminosity and global H2 mass content of galaxies, because of its brightness and observability with currently available sub-mm and radio instruments; (4) the luminosity functions of high-J CO lines show stronger evolution than the luminosity functions of low-J CO lines; (5) our model barely reproduces the available constraints on the CO and [C II] luminosity function of galaxies at z ≥ 1.5 and the CO luminosity of individual galaxies at intermediate redshifts. We argue that this is driven by a lack of cold gas in galaxies at intermediate redshifts as predicted by cosmological simulations of galaxy formation.

Original languageEnglish (US)
Pages (from-to)93-110
Number of pages18
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Sep 1 2016

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxies: ISM
  • Galaxies: evolution
  • Galaxies: formation
  • ISM: atoms
  • ISM: lines and bands
  • ISM: molecules

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