Spatially Resolved CO SLED of the Luminous Merger Remnant NGC 1614 with ALMA
Journal article, 2017
We present high-resolution (1.?0) Atacama Large Millimeter/submillimeter Array (ALMA) observations of CO (1-0) and CO (2-1) rotational transitions toward the nearby IR-luminous merger NGC 1614 supplemented with ALMA archival data of CO (3-2) and CO (6-5) transitions. The CO (6-5) emission arises from the starburst ring (central 590 pc in radius), while the lower-J CO lines are distributed over the outer disk (?3.3 kpc in radius). Radiative transfer and photon-dominated region (PDR) modeling reveals that the starburst ring has a single warmer gas component with more a intense far-ultraviolet radiation field (nh2 ? 104.6 cm-3, Tkin ?42 K, and G0 ?102.7) relative to the outer disk (nh2 ? 105.1 cm-3, Tkin ? 22 K, and G0 ?100.9 cm-3, K, and ). A two-phase molecular interstellar medium with a warm and cold (>70 and ?19 K) component is also an applicable model for the starburst ring. A possible source for heating the warm gas component is mechanical heating due to stellar feedback rather than PDR. Furthermore, we find evidence for non-circular motions along the north-south optical bar in the lower-J CO images, suggesting a cold gas inflow. We suggest that star formation in the starburst ring is sustained by the bar-driven cold gas inflow and that starburst activities radiatively and mechanically power the CO excitation. The absence of a bright active galactic nucleus can be explained by a scenario where cold gas accumulating on the starburst ring is exhausted as the fuel for star formation or is launched as an outflow before being able to feed to the nucleus.
submillimeter: galaxies
galaxies: individual (NGC 1614
galaxies: ISM
radiative transfer
Arp 186)
galaxies: interactions
Author
Toshiki Saito
National Institutes of Natural Sciences - National Astronomical Observatory of Japan
University of Tokyo
D. Iono
Sokendai Graduate University for Advanced Studies
National Institutes of Natural Sciences - National Astronomical Observatory of Japan
C. K. Xu
California Institute of Technology
Kazimierz Sliwa
Max Planck Institut fur Astronomie
Junko Ueda
Harvard-Smithsonian Center for Astrophysics
D. Espada
Sokendai Graduate University for Advanced Studies
National Institutes of Natural Sciences - National Astronomical Observatory of Japan
Hiroyuki Kaneko
National Institutes of Natural Sciences - National Astronomical Observatory of Japan
Sabine König
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
K. Nakanishi
National Institutes of Natural Sciences - National Astronomical Observatory of Japan
Sokendai Graduate University for Advanced Studies
Minju Lee
University of Tokyo
National Institutes of Natural Sciences - National Astronomical Observatory of Japan
Min S. Yun
University of Massachusetts
Susanne Aalto
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
John E. Hibbard
National Radio Astronomy Observatory
Takuji Yamashita
JAXA Institute of Space and Astronautical Science
Kentaro Motohara
University of Tokyo
R. Kawabe
University of Tokyo
National Institutes of Natural Sciences - National Astronomical Observatory of Japan
Sokendai Graduate University for Advanced Studies
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 835 2 174Subject Categories (SSIF 2011)
Atom and Molecular Physics and Optics
DOI
10.3847/1538-4357/835/2/174