An intensity mapping detection of aggregate co line emission at 3mm

Garrett K. Keating, Daniel P. Marrone, Geoffrey C. Bower, Ryan P. Keenan

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


We present a detection of molecular gas emission at z ∼ 1-5 using the technique of line intensity mapping. We make use of a pair of 3mm interferometric data sets, the first from the Atacama Large Millimeter/submillimeter Array (ALMA) Spectroscopic Survey in the Hubble Ultra Deep Field, and the second from a series of Atacama Compact Array (ACA) observations conducted between 2016 and 2018, targeting the COSMOS field. At 100 GHz, we measure nonzero power at 97.8% and 99.9% confidence in the ACA and ALMA data sets, respectively. In the joint result, we reject the zeropower hypothesis at 99.99% confidence, finding Is (ν)= 770 ±210 μK2 Hz sr . After accounting for sample variance effects, the estimated spectral shot power is I2s (ν) = - 1010+550-390μ μK2 Hz sr s . We derive a model for the various line species our measurement is expected to be sensitive to, and estimate the shot power to be - 120+70-50 μK2 h-3 Mpc3 - 210+110-80 μK2 h-3 Mpc3 , and 100+50-40 μK2 h-3 Mpc3 for CO(2-1) at z = 1.3, CO(3-2) at z = 2.5, and CO(4-3) at z = 3.6, respectively. Using line ratios appropriate for high-redshift galaxies, we find these results to be in good agreement with those from the CO Power Spectrum Survey. Adopting αCO = 3.6M⊙ (Kkms-1 pc2)-1, we estimate a cosmic molecular gas density of ρH2 (z) ∼ 108M⊙ Mpc-3 between z = 1-3.

Original languageEnglish (US)
Article numberabb08e
JournalAstrophysical Journal
Issue number2
StatePublished - Oct 1 2020


  • Cosmological evolution (336)
  • Early universe (435)
  • Molecular gas (1073)
  • Star formation (1569)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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