The Dual Role of Starbursts and Active Galactic Nuclei in Driving Extreme Molecular Outflows

We report molecular gas observations of IRAS 20100−4156 and IRAS 03158+4227, two local ultraluminous infrared galaxies (ULIRGs) hosting some of the fastest and most massive molecular outflows known. Using Atacama Large Millimeter Array and Plateau de Bure Interferometer observations, we spatially re...

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Bibliographic Details
Published in:The Astrophysical journal 2018-05, Vol.859 (1), p.35
Main Authors: Gowardhan, Avani, Spoon, Henrik, Riechers, Dominik A., González-Alfonso, Eduardo, Farrah, Duncan, Fischer, Jacqueline, Darling, Jeremy, Fergulio, Chiara, Afonso, Jose, Bizzocchi, Luca
Format: Article
Language:English
Subjects:
Active galactic nuclei
Astrophysics
Depletion
Fluxes
Galaxies
galaxies: active
galaxies: evolution
galaxies: starburst
Infrared astronomy
Infrared spectra
Interferometers
ISM: jets and outflows
ISM: molecules
Luminosity
Molecular gases
Outflow
Radio telescopes
Star & galaxy formation
Star formation
techniques: interferometric
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Summary:We report molecular gas observations of IRAS 20100−4156 and IRAS 03158+4227, two local ultraluminous infrared galaxies (ULIRGs) hosting some of the fastest and most massive molecular outflows known. Using Atacama Large Millimeter Array and Plateau de Bure Interferometer observations, we spatially resolve the CO (1−0) emission from the outflowing molecular gas in both and find maximum outflow velocities of vmax ∼ 1600 and ∼1700 km s−1 for IRAS 20100−4156 and IRAS 03158+4227, respectively. We find total gas mass outflow rates of and ∼350 M yr−1, respectively, corresponding to molecular gas depletion timescales and ∼16 Myr. This is nearly 3 times shorter than the depletion timescales implied by star formation, and ∼46 Myr, respectively. To determine the outflow driving mechanism, we compare the starburst luminosity (L*) and active galactic nucleus (AGN) luminosity (LAGN) to the outflowing energy and momentum fluxes, using mid-infrared spectral decomposition to discern LAGN. Comparison to other molecular outflows in ULIRGs reveals that outflow properties correlate similarly with L* and LIR as with LAGN, indicating that AGN luminosity alone may not be a good tracer of feedback strength and that a combination of AGN and starburst activity may be driving the most powerful molecular outflows. We also detect the OH 1.667 GHz maser line from both sources and demonstrate its utility in detecting molecular outflows.
ISSN:0004-637X
1538-4357
DOI:10.3847/1538-4357/aabccc