Accurso, G;
Saintonge, A;
Catinella, B;
Cortese, L;
Dave, R;
Dunsheath, SH;
Genzel, R;
... Wang, J; + view all
(2017)
Deriving a multivariate alpha(CO) conversion function using the [C II]/CO (1-0) ratio and its application to molecular gas scaling relations.
Monthly Notices of the Royal Astronomical Society
, 470
(4)
pp. 4750-4766.
10.1093/mnras/stx1556.
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Abstract
We present Herschel PACS observations of the [C II] 158 μm emission line in a sample of 24 intermediate mass (9 < log M∗/M < 10) and low metallicity (0.4 < Z/Z < 1.0) galaxies from the xCOLD GASS survey. In combination with IRAM CO (1−0) measurements, we establish scaling relations between integrated and molecular region L[CII]/LCO (1–0) ratios as a function of integrated galaxy properties. A Bayesian analysis reveals that only two parameters, metallicity and offset from the main sequence, (MS), are needed to quantify variations in the luminosity ratio; metallicity describes the total dust content available to shield CO from UV radiation, while (MS) describes the strength of this radiation field. We connect the L[CII]/LCO (1–0) ratio to the CO-to-H2 conversion factor and find a multivariate conversion function, which can be used up to z ∼ 2.5. This function depends primarily on metallicity, with a second-order dependence on (MS). We apply this to the full xCOLD GASS and PHIBSS1 surveys and investigate molecular gas scaling relations. We find a flattening of the relation between gas mass fraction and stellar mass at log M∗ < 10.0. While the molecular gas depletion time varies with sSFR, it is mostly independent of mass, indicating that the low LCO/SFR ratios long observed in low-mass galaxies are entirely due to photodissociation of CO and not to an enhanced star formation efficiency.
| Type: | Article |
|---|---|
| Title: | Deriving a multivariate alpha(CO) conversion function using the [C II]/CO (1-0) ratio and its application to molecular gas scaling relations |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1093/mnras/stx1556 |
| Publisher version: | http://doi.org/10.1093/mnras/stx1556 |
| Language: | English |
| Additional information: | © 2017 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. This version is the version of record. For information on re-use, please refer to the publisher’s terms and conditions. |
| Keywords: | Science & Technology, Physical Sciences, Astronomy & Astrophysics, surveys, galaxies: evolution, galaxies: fundamental parameters, galaxies: ISM, radio lines: galaxies, STAR-FORMING GALAXIES, DIGITAL SKY SURVEY, MASS-METALLICITY RELATION, ARECIBO SDSS SURVEY, GAMMA-RAY EMISSION, IRAM LEGACY SURVEY, NEARBY GALAXIES, PHOTODISSOCIATION REGIONS, DATA RELEASE, INTERSTELLAR-MEDIUM |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Physics and Astronomy |
| URI: | https://discovery.ucl.ac.uk/id/eprint/1556875 |
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