Spatially Resolved CO SLED of the Luminous Merger Remnant NGC 1614 with ALMA

Journal Article · Wed Feb 01 04:00:00 EST 2017 · Astrophysical Journal

DOI:https://doi.org/10.3847/1538-4357/835/2/174· OSTI ID:22869498

Saito, Toshiki; Lee, Minju; Kawabe, Ryohei ^[1]; Iono, Daisuke; Espada, Daniel; Nakanishi, Kouichiro ^[2]; Xu, Cong K. ^[3]; Sliwa, Kazimierz ^[4]; Ueda, Junko ^[5]; Kaneko, Hiroyuki ^[6]; König, Sabine; Aalto, Susanne ^[7]; Yun, Min S. ^[8]; Hibbard, John E. ^[9]; Yamashita, Takuji ^[10]; Motohara, Kentaro ^[11]

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1. Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
2. National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-8588 (Japan)
3. Infrared Processing and Analysis Center (IPAC), California Institute of Technology, 770 South Wilson Avenue, Pasadena, CA 91125 (United States)
4. Max-Planck Institute for Astronomy, Königstuhl 17, D-69117 Heidelberg (Germany)
5. Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
6. Nobeyama Radio Observatory, Minamimaki, Minamisaku, Nagano 384-1305 (Japan)
7. Chalmers University of Technology, Department of Earth and Space Sciences, Onsala Space Observatory, SE-43992 Onsala (Sweden)
8. Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
9. National Radio Astronomy Observatory, 520 Edgemont Road, Charlottesville, VA 22903 (United States)
10. Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yoshinodai, Sagamihara, Kanagawa 229-8510 (Japan)
11. Institute of Astronomy, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)

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 (n{sub H{sub 2}}∼10{sup 4.6} cm{sup −3}, T{sub kin}∼42 K, and G{sub 0}∼10{sup 2.7}) relative to the outer disk (n{sub H{sub 2}}∼10{sup 5.1} cm{sup −3}, T{sub kin}∼22 K, and G{sub 0}∼10{sup 0.9}). 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.

• OSTI ID: 22869498
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 835; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
CARBON MONOXIDE
COMPUTERIZED SIMULATION
EMISSION
EXCITATION
FAR ULTRAVIOLET RADIATION
GALAXIES
GALAXY NUCLEI
INTERACTIONS
PHOTONS
RADIANT HEAT TRANSFER
RESOLUTION
STARS