Volume 628, August 2019
|Number of page(s)||30|
|Published online||08 August 2019|
Molecular gas and dust properties of galaxies from the Great Observatories All-sky LIRG Survey⋆
European Southern Observatory (ESO), Alonso de Córdova 3107, Casilla, 19001 Vitacura, Santiago de Chile, Chile
2 Instituto de Astrofísica de Andalucía – CSIC, PO Box 3004 18008 Granada, Spain
3 Instituto de Astrofísica, Facultad de Física, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22, Chile
4 Department of Astronomy, University of Florida, PO Box 112055 Gainesville, FL 32611, USA
5 Department of Astronomy, University of Virginia, Charlottesville, VA 22903, USA
6 National Radio Astronomy Observatory, Charlottesville, VA 22903, USA
7 Núcleo de Astronomía de la Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército Libertador 441, Santiago, Chile
8 Visiting Scientist: Facultad de Ciencias, Univ. de Zaragoza, Zaragoza, Spain
9 Department of Physics and Astronomy, University of California, 4129 Frederick Reines Hall, Irvine, CA 92697, USA
10 ICREA and Institut de Ciències del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Martí i Franquès 1, 08028 Barcelona, Spain
11 Spitzer Science Center, California Institute of Technology, Pasadena, CA 91106, USA
12 Department of Earth and Space Sciences, Chalmers University of Technology, Onsala Space Observatory, 43992 Onsala, Sweden
13 Infrared Processing and Analysis Center, California Institute of Technology, Pasadena, CA 91125, USA
14 Gemini North Observatory, 670 N. A‘ohoku Place, Hilo, HI 96720, USA
15 Institute for Astronomy, University of Hawaii, 2680 Woodlawn Dr, Honolulu, HI 96822, USA
16 Joint ALMA Observatory, Alonso de Córdova 3107, Vitacura, Santiago, Chile
17 Institute for Astronomy, Astrophysics, Space Applications & Remote Sensing, National Observatory of Athens, 15236 Penteli, Greece
18 Green Bank Observatory, Green Bank, WV 24944, USA
19 National Optical Astronomy Observatory, 950 North Cherry Avenue, Tucson, AZ 85719, USA
Accepted: 29 June 2019
We present IRAM-30 m Telescope 12CO and 13CO observations of a sample of 55 luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) in the local universe. This sample is a subset of the Great Observatory All-Sky LIRG Survey (GOALS), for which we use ancillary multi-wavelength data to better understand their interstellar medium and star formation properties. Fifty-three (96%) of the galaxies are detected in 12CO, and 29 (52%) are also detected in 13CO above a 3σ level. The median full width at zero intensity (FWZI) velocity of the CO line emission is 661 km s−1, and ∼54% of the galaxies show a multi-peak CO profile. Herschel photometric data is used to construct the far-IR spectral energy distribution of each galaxy, which are fit with a modified blackbody model that allows us to derive dust temperatures and masses, and infrared luminosities. We make the assumption that the gas-to-dust mass ratio of (U)LIRGs is comparable to local spiral galaxies with a similar stellar mass (i.e., gas/dust of mergers is comparable to their progenitors) to derive a CO-to-H2 conversion factor of ⟨α⟩ = 1.8−0.8+1.3 M⊙ (K km s−1 pc2)−1; such a value is comparable to that derived for (U)LIRGs based on dynamical mass arguments. We derive gas depletion times of 400 − 600 Myr for the (U)LIRGs, compared to the 1.3 Gyr for local spiral galaxies. Finally, we re-examine the relationship between the 12CO/13CO ratio and dust temperature, confirming a transition to elevated ratios in warmer systems.
Key words: ISM: molecules / galaxies: ISM / galaxies: active / galaxies: starburst / radio lines: galaxies
A copy of the reduced spectra is available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (184.108.40.206) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A71
© ESO 2019
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