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arXiv · 1907.03854

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

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

We present IRAM-30m Telescope $^{12}$CO and $^{13}$CO 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 $^{12}$CO, and 29 (52%) are also detected in $^{13}$CO above a 3$\sigma$ level. The median full width at zero intensity (FWZI) velocity of the CO line emission is 661km s$^{-1}$, and $\sim$54% of the galaxies show a multi-peak CO profile. Herschel photometric data is used to construct the far-IR spectral energy distribution of each galaxy, which are fit with a modified blackbody model that allows us to derive dust temperatures and masses, and infrared luminosities. We make the assumption that the gas-to-dust mass ratio of (U)LIRGs is comparable to local spiral galaxies with a similar stellar mass (i.e., gas/dust of mergers is comparable to their progenitors) to derive a CO-to-H$_2$ conversion factor of $\langle\alpha\rangle=1.8^{+1.3}_{-0.8}M_\odot$(K km s$^{-1}$pc$^{2}$)$^{-1}$; 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 1.3Gyr for local spiral galaxies. Finally, we re-examine the relationship between the $^{12}$CO/$^{13}$CO ratio and dust temperature, confirming a transition to elevated ratios in warmer systems.

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R. Herrero-Illana, G. C. Privon, A. S. Evans, T. Díaz-Santos, M. Á. Pérez-Torres, V. U, A. Alberdi, K. Iwasawa, L. Armus, S. Aalto, J. Mazzarella, J. Chu, D. B. Sanders, L. Barcos-Muñoz, V. Charmandaris, S. T. Linden, I. Yoon, D. T. Frayer, H. Inami, D. -C. Kim, H. J. Borish, J. Conway, E. J Murphy, Y. Song, S. Stierwalt, J. Surace. 2019-07-08. Molecular gas and dust properties of galaxies from the Great Observatories All-sky LIRG Survey. https://doi.org/10.1051/0004-6361%2F201834088

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