Molecular gas and dust properties of galaxies from the Great Observatories All-sky LIRG Survey
Abstract
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.
A copy of the reduced spectra is available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A71- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- August 2019
- DOI:
- 10.1051/0004-6361/201834088
- arXiv:
- arXiv:1907.03854
- Bibcode:
- 2019A&A...628A..71H
- Keywords:
-
- ISM: molecules;
- galaxies: ISM;
- galaxies: active;
- galaxies: starburst;
- radio lines: galaxies;
- Astrophysics - Astrophysics of Galaxies
- E-Print:
- 32 pages, 10 figures. Accepted for publication in Astronomy &