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

Arp 186)

radiative transfer

galaxies: ISM

galaxies: interactions

Author

Toshiki Saito

National Astronomical Observatory of Japan

University of Tokyo

D. Iono

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

C. K. Xu

California Institute of Technology (Caltech)

Kazimierz Sliwa

Max Planck Society

Junko Ueda

Harvard-Smithsonian Center for Astrophysics

D. Espada

The Graduate University for Advanced Studies (SOKENDAI)

National Astronomical Observatory of Japan

Hiroyuki Kaneko

National Astronomical Observatory of Japan

Sabine König

Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics

K. Nakanishi

National Astronomical Observatory of Japan

The Graduate University for Advanced Studies (SOKENDAI)

Minju Lee

National Astronomical Observatory of Japan

University of Tokyo

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

The Graduate University for Advanced Studies (SOKENDAI)

University of Tokyo

National Astronomical Observatory of Japan

Astrophysical Journal

0004-637X (ISSN) 1538-4357 (eISSN)

Vol. 835 2 174

Subject Categories

Atom and Molecular Physics and Optics

DOI

10.3847/1538-4357/835/2/174

More information

Latest update

9/10/2019