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

Creators: Herrero-Illana, R.; Privon, G. C.; Evans, A. S.; Díaz-Santos, T.; Pérez-Torres, M. A.; 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 ^(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 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-H_2 conversion factor of ⟨α⟩ = 1.8_(−0.8)^(+1.3)M⊙ (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 1.3 Gyr 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.

Additional Information

© 2019 ESO. Article published by EDP Sciences. Received 14 August 2018; Accepted 29 June 2019; Published online 08 August 2019. We thank the anonymous referee for the useful comments. We also thank Nick Scoville for his discussion and comments on the paper. We are grateful to Manuel González for his help in the preparation of the scripts and during the observations. This work is based on observations carried out under project numbers 099-10, 092-11, 227-11, 076-12, 222-13, and D01-13 with the 30m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain). We thank the director of IRAM 30m for the approval of the discretionary time requested. RHI, MAPT, and AA acknowledge support from the Spanish MINECO through grants AYA2012-38491-C02-02 and AYA2015-63939-C2-1-P. G.C.P. was supported by a FONDECYT Postdoctoral Fellowship (No. 3150361). G.C.P. also acknowledges support from the University of Florida. G.C.P. and A.S.E. were supported by the NSF grant AST 1109475. A.S.E. was also supported by the Taiwan, R.O.C. Ministry of Science and technology grant MoST 102-2119-M-001-MY3. T.D.-S. acknowledges support from ALMA-CONICYT project 31130005 and FONDECYT regular project 1151239. This work was supported in part by National Science Foundation grant No. PHYS-1066293 and the hospitality of the Aspen Center for Physics. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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