Molecular gas and dust properties of galaxies from the Great Observatories All-sky LIRG Survey

August 2019 • 2019A&A...628A..71H

Authors • Herrero-Illana, R. • Privon, G. C. • Evans, A. S. • Díaz-Santos, T. • Pérez-Torres, M. Á. • U, V. • Alberdi, A. • Iwasawa, K. • Armus, L. • Aalto, S. • Mazzarella, J. • Chu, J. • Sanders, D. B. • Barcos-Muñoz, L. • Charmandaris, V. • Linden, S. T. • Yoon, I. • Frayer, D. T. • Inami, H. • Kim, D. -C. • Borish, H. J. • Conway, J. • Murphy, E. J. • Song, Y. • Stierwalt, S. • Surace, J.

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 ( or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/628/A71


IPAC Authors

Joe Mazzarella

Senior Scientist