The Dense Molecular Gas and Nuclear Activity in the ULIRG IRAS 13120-5453
Artikel i vetenskaplig tidskrift, 2017
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 ?IR of 4.7 × 1012 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 H2O lines and find a nuclear dust temperature of ?40 K. IRAS 13120-5453 has a lower dust temperature and ?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.
galaxies: interactions
galaxies: individual (IRAS 13120-5453)
galaxies: ISM
galaxies: starburst
galaxies: active
Författare
G. Privon
Pontificia Universidad Catolica de Chile
Universidad de Concepción
Susanne Aalto
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
Niklas Falstad
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
Sebastien Muller
Chalmers, Rymd- och geovetenskap, Onsala rymdobservatorium
E. Gonzalez-Alfonso
Universidad de Alcala
Kazimierz Sliwa
Max-Planck-Gesellschaft
E. Treister
Pontificia Universidad Catolica de Chile
Universidad de Concepción
Francesco Costagliola
Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik
L. Armus
Spitzer Science Center
A. S. Evans
University of Virginia
National Radio Astronomy Observatory
S. G. Burillo
Observatorio Astronómico Nacional (OAN)
T. Izumi
University of Tokyo
K. Sakamoto
Academia Sinica
P. van der Werf
Universiteit Leiden
J. Chu
University of Hawaii
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 835 2 Article Number: 213- 213Ämneskategorier
Astronomi, astrofysik och kosmologi
DOI
10.3847/1538-4357/835/2/213