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The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120–5453

Privon, G. C. and Aalto, S. and Falstad, N. and Muller, S. and González-Alfonso, E. and Sliwa, K. and Treister, E. and Costagliola, F. and Armus, L. and Evans, A. S. and García-Burillo, S. and Izumi, T. and Sakamoto, K. and van der Werf, P. and Chu, J. K. (2017) The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120–5453. Astrophysical Journal, 835 (2). Art. No. 213. ISSN 0004-637X.

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We present new Atacama Large Millimeter/submillimeter Array Band 7 (~340 GHz) observations of the dense gas tracers HCN, HCO^+, and CS in the local, single-nucleus, ultraluminous infrared galaxy IRAS 13120–5453. We find centrally enhanced HCN (4–3) emission, relative to HCO^+ (4–3), but do not find evidence for radiative pumping of HCN. Considering the size of the starburst (0.5 kpc) and the estimated supernovae rate of ~1.2 yr^(−1), the high HCN/HCO^+ ratio can be explained by an enhanced HCN abundance as a result of mechanical heating by the supernovae, though the active galactic nucleus and winds may also contribute additional mechanical heating. The starburst size implies a high Σ_(IR) of 4.7 × 10^(12) L⊙ kpc^(−2), slightly below predictions of radiation-pressure limited starbursts. The HCN line profile has low-level wings, which we tentatively interpret as evidence for outflowing dense molecular gas. However, the dense molecular outflow seen in the HCN line wings is unlikely to escape the Galaxy and is destined to return to the nucleus and fuel future star formation. We also present modeling of Herschel observations of the H_2O lines and find a nuclear dust temperature of ~40 K. IRAS 13120–5453 has a lower dust temperature and Σ_(IR) than is inferred for the systems termed "compact obscured nuclei (CONs)" (such as Arp 220 and Mrk 231). If IRAS 13120–5453 has undergone a CON phase, we are likely witnessing it at a time when the feedback has already inflated the nuclear ISM and diluted star formation in the starburst/active galactic nucleus core.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Privon, G. C.0000-0003-3474-1125
Treister, E.0000-0001-7568-6412
Armus, L.0000-0003-3498-2973
Evans, A. S.0000-0003-2638-1334
Sakamoto, K.0000-0003-0494-8838
van der Werf, P.0000-0001-5434-5942
Additional Information:© 2017 The American Astronomical Society. Received 2016 September 9; revised 2016 November 29; accepted 2016 December 8; published 2017 January 31. The authors thank the anonymous referee for his/her comments, which have improved the quality of the paper. This paper makes use of the following ALMA data: ADS/JAO.ALMA#2012.1.00817.S. ALMA is a partnership of ESO (representing its member states), NSF (USA) and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan) and KASI (Republic of Korea), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO and NAOJ. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. G.C.P. was supported by a FONDECYT Postdoctoral Fellowship (No. 3150361) and acknowledges the hospitality of the National Socio-environmental Synthesis Center (SESYNC), where portions of this manuscript were written. G.C.P. and E.T. acknowledge support from the CONICYT Anillo project ACT1101. F.C. acknowledges support from Swedish National Science Council grant 637-2013-7261. S.G.B. acknowledges support from Spanish grants AYA2013-42227-P and ESP2015-68964-P. K.S. acknowledges grant 105-2119-M-001-036 from Taiwanese Ministry of Science and Technology. Portions of this work were performed at the Aspen Center for Physics, which is supported by National Science Foundation grant PHY-1066293. This work was partially supported by a grant from the Simons Foundation. The authors thank Claudia Cicone, Francois Schweizer, and Claudio Ricci for comments on an earlier version of the manuscript. G.C.P. thanks Paul Torrey, David Patton, Chris Hayward, Desika Narayanan, Claudia Cicone, Nick Scoville, and Patricia Bessiere for helpful discussions. 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. This research has made use of NASA's Astrophysics Data System. This research made use of ipython (Pérez & Granger 2007), numpy (Van Der Walt et al. 2011), Astropy (Astropy Collaboration et al. 2013,, a community-developed core Python package for Astronomy), emcee (Foreman-Mackey et al. 2013), and the dust_emissivity package ( The figures in this paper were created using matplotlib (Hunter 2007) and APLpy (Robitaille & Bressert 2012, an open-source plotting package for Python hosted at
Group:Infrared Processing and Analysis Center (IPAC)
Funding AgencyGrant Number
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3150361
Comisión Nacional de Investigación Científica y Tecnológica (CONICYT)ACT1101
Swedish National Science Council637-2013-7261
Ministerio de Economía y Competitividad (MINECO)AYA2013-42227-P
Ministerio de Economía y Competitividad (MINECO)ESP2015-68964-P
Ministry of Science and Technology (Taipei)105-2119-M-001-036
Simons FoundationUNSPECIFIED
Subject Keywords:galaxies: active – galaxies: individual (IRAS 13120-5453) – galaxies: interactions – galaxies: ISM – galaxies: starburst
Issue or Number:2
Record Number:CaltechAUTHORS:20170201-101210401
Persistent URL:
Official Citation:G. C. Privon et al 2017 ApJ 835 213
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:73924
Deposited By: Tony Diaz
Deposited On:01 Feb 2017 18:44
Last Modified:09 Mar 2020 13:19

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