Cross-calibration of CO- versus dust-based gas masses and assessment of the dynamical mass budget in Herschel-SDSS Stripe82 galaxies

Caroline Bertemes, Stijn Wuyts, Dieter Lutz, Natascha M Förster schreiber, Reinhard Genzel, Robert F Minchin, Carole G Mundell, David Rosario, Amélie Saintonge, Linda Tacconi

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We present a cross-calibration of CO- and dust-based molecular gas masses at z ≤ 0.2. Our results are based on a survey with the IRAM 30-m telescope collecting CO(1–0) measurements of 78 massive (logM⋆/M⊙> 10) galaxies with known gas-phase metallicities and with IR photometric coverage from Wide-field Infrared Survey Explorer(WISE; 22μm) and Herschel Spectral and Photometric Imaging Receiver (SPIRE; 250, 350, 500μm). We find a tight relation (∼0.17 dex scatter) between the gas masses inferred from CO and dust continuum emission, with a minor systematic offset of 0.05 dex. The two methods can be brought into agreement by applying a metallicity-dependent adjustment factor (∼0.13 dex scatter). We illustrate that the observed offset is consistent with a scenario in which dust traces not only molecular gas but also part of the Hi reservoir, residing in the H2-dominated region of the galaxy. Observations of the CO(2–1) to CO(1–0) line ratio for two-thirds of the sample indicate a narrow range in excitation properties, with a median ratio of luminosities ⟨R21⟩ ∼ 0.64. Finally, we find dynamical mass constraints from spectral line profile fitting to agree well with the anticipated mass budget enclosed within an effective radius, once all mass components (stars, gas, and dark matter) are accounted for.
Original languageEnglish
Pages (from-to)1442-1458
Number of pages17
JournalMonthly Notices of the Royal Astronomical Society
Issue number2
Early online date22 May 2018
Publication statusPublished - 1 Aug 2018

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