A hidden molecular outflow in the LIRG Zw 049.057

Abstract

Feedback in the form of mass outflows driven by star formation or active galactic nuclei is a key component of galaxy evolution. The luminous infrared galaxy Zw 049.057 harbours a compact obscured nucleus with a possible far-IR signature of outflowing molecular gas. Due to the high optical depths at far-IR wavelengths, the interpretation of the outflow signature is uncertain. At mm and radio wavelengths, the radiation is better able to penetrate the large columns of gas and dust. We used high resolution observations from the SMA, ALMA, and the VLA to image the CO 2-1 and 6-5 emission, the 690 GHz continuum, the radio cm continuum, and absorptions by rotationally excited OH. The CO line profiles exhibit wings extending 300 km/s beyond the systemic velocity. At cm wavelengths, we find a compact (40 pc) continuum component in the nucleus, with weaker emission extending several 100 pc approximately along the major and minor axes of the galaxy. In the OH absorption lines toward the compact continuum, wings extending to a similar velocity as for the CO are seen on the blue side of the profile. The weak cm continuum emission along the minor axis is aligned with a highly collimated, jet-like dust feature previously seen in near-IR images of the galaxy. Comparison of the apparent optical depths in the OH lines indicate that the excitation conditions in Zw 049.057 differ from those in other OH megamaser galaxies. We interpret the wings in the spectral lines as signatures of a molecular outflow. A relation between this outflow and the minor axis radio feature is possible, although further studies are required to investigate this possible association and understand the connection between the outflow and the nuclear activity. Finally, we suggest that the differing OH excitation conditions are further evidence that Zw 049.057 is in a transition phase between megamaser and kilomaser activity.

12 pages, 12 figures, Accepted for publication in Astronomy and Astrophysics

References in corpus (8)

• Massive molecular outflows and negative feedback in ULIRGs observed by Herschel-PACS
• Molecular line emission in NGC1068 imaged with ALMA. I An AGN-driven outflow in the dense molecular gas
• Molecular outflows in local ULIRGs: energetics from multi-transition OH analysis
• SMA Imaging of CO(3-2) Line and 860 micron Continuum of Arp 220 : Tracing the Spatial Distribution of Luminosity
• A Luminous Infrared Merger with Two Bipolar Molecular Outflows: ALMA and SMA Observations of NGC 3256
• High-resolution HNC 3-2 SMA observations of Arp220
• The radio core structure of the luminous infrared galaxy NGC 4418
• Inflowing gas onto a compact obscured nucleus in Arp 299A: Herschel spectroscopic studies of H2O and OH

Cited by in corpus (9)

• Molecular outflows in local galaxies: Method comparison and a role of intermittent AGN driving
• A Review of Recent Observations of Galactic Winds Driven by Star Formation
• CON-quest: Searching for the most obscured galaxy nuclei
• The hidden heart of the luminous infrared galaxy IC 860 I. A molecular inflow feeding opaque, extreme nuclear activity
• Hidden or missing outflows in highly obscured galaxy nuclei?
• ALMA resolves the remarkable molecular jet and rotating wind in the extremely radio-quiet galaxy NGC 1377
• GOALS-JWST: Gas Dynamics and Excitation in NGC7469 revealed by NIRSpec
• The Molecular ISM in the Super Star Clusters of the Starburst NGC 253
• An Imaging and Spectroscopic Exploration of the Dusty Compact Obscured Nucleus Galaxy Zw~049.057