Merger-induced shocks in the nearby LIRG VV 114 through methanol observations with ALMA
- Department of Astronomy, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
- National Astronomical Observatory of Japan, 2-21-1 Osawa, Mitaka, Tokyo, 181-0015 (Japan)
- Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States)
- Kavli Institute for the Physics and Mathematics of the Universe (WPI), The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, 277-8583, Chiba (Japan)
- Physics Department, College of Engineering, Nihon University, 1 Nakagawara, Tokusada, Tamura, Koriyama, Fukushima, 963-8642 (Japan)
- Department of Astronomy, University of Massachusetts, Amherst, MA 01003 (United States)
- Subaru Telescope, 650 North Aohoku Place, Hilo, HI 96720 (United States)
- Natural Science Laboratory, Toyo University, 5-28-20, Hakusan, Bunkyo-ku, Tokyo 112-8606 (Japan)
- Institute of Astronomy, The University of Tokyo, 2-21-1 Osawa, Mitaka, Tokyo 181-0015 (Japan)
We report the detection of two CH{sub 3}OH lines (J{sub K} = 2{sub K}–1{sub K} and 3{sub K}–2{sub K}) between the progenitor’s disks (“Overlap”) of the mid-stage merging galaxy VV 114 obtained using the Atacama Large Millimeter/submillimeter Array (ALMA) Band 3 and Band 4. The detected CH{sub 3}OH emission shows an extended filamentary structure (∼3 kpc) across the progenitor’s disks with relatively large velocity width (FWZI ∼ 150 km s{sup −1}). The emission is only significant in the “overlap” and not detected in the two merging nuclei. Assuming optically thin emission and local thermodynamic equilibrium, we found the CH{sub 3}OH column density relative to H{sub 2} (X{sub CH{sub 3OH}}) peaks at the “Overlap” (∼8 × 10{sup −9}), which is almost an order of magnitude larger than that at the eastern nucleus. We suggest that kpc-scale shocks driven by galaxy–galaxy collision may play an important role to enhance the CH{sub 3}OH abundance at the “Overlap.” This scenario is consistent with shock-induced large velocity dispersion components of ionized gas that have been detected in optical wavelength at the same region. Conversely, low X{sub CH{sub 3OH}} at the nuclear regions might be attributed to the strong photodissociation by nuclear starbursts and/or a putative active galactic nucleus, or inefficient production of CH{sub 3}OH on dust grains due to initial high-temperature conditions (i.e., desorption of the precursor molecule, CO, into gas phase before forming CH{sub 3}OH on dust grains). These ALMA observations demonstrate that CH{sub 3}OH is a unique tool to address kpc-scale shock-induced gas dynamics and star formation in merging galaxies.
- OSTI ID:
- 22869607
- Journal Information:
- Astrophysical Journal, Vol. 834, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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