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Published May 20, 2014 | Submitted + Published
Journal Article Open

ALMA Observations of Warm Molecular Gas and Cold Dust in NGC 34

Abstract

We present Atacama Large Millimeter Array (ALMA) Cycle-0 observations of the CO (6-5) line emission (rest-frame frequency = 691.473 GHz) and of the 435 μm dust continuum emission in the nuclear region of NGC 34, a local luminous infrared galaxy at a distance of 84 Mpc (1'' = 407 pc) which contains a Seyfert 2 active galactic nucleus (AGN) and a nuclear starburst. The CO emission is well resolved by the ALMA beam (0.''26 × 0.''23), with an integrated flux of f_(CO(6-5)) = 1004 (± 151) Jy km s^(–1). Both the morphology and kinematics of the CO (6-5) emission are rather regular, consistent with a compact rotating disk with a size of 200 pc. A significant emission feature is detected on the redshifted wing of the line profile at the frequency of the H^(13)CN (8-7) line, with an integrated flux of 17.7 ± 2.1(random) ± 2.7(systematic) Jy km s^(–1). However, it cannot be ruled out that the feature is due to an outflow of warm dense gas with a mean velocity of 400 km s^(–1). The continuum is resolved into an elongated configuration, and the observed flux corresponds to a dust mass of M_(dust) = 10^(6.97 ± 0.13) M☉. An unresolved central core (radius ≃50 pc) contributes 28% of the continuum flux and 19% of the CO (6-5) flux, consistent with insignificant contributions of the AGN to both emissions. Both the CO (6-5) and continuum spatial distributions suggest a very high gas column density (≳10^4 M☉ pc^(–2)) in the nuclear region at radius ≾100 pc.

Additional Information

© 2014 American Astronomical Society. Received 2013 November 25; accepted 2014 April 3; published 2014 May 2. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. C.K.X. acknowledges useful discussions with George Privon, Eckard Sturm, Francois Schweizer, and Ximena Fernandez. Kim Scott and Tony Remijan from NAASC are thanked for their help on data reduction. Y.G. is partially supported by NSFC-11173059, NSFC-11390373, and CAS-XDB09000000. Y.Z. thanks the NSF of Jiangsu Province for partial support under grant BK2011888. V.C. acknowledges partial support from the EU FP7 grant PIRSES-GA-2012-316788. This paper makes use of the following ALMA data: ADS/ JAO.ALMA#2011.0.00182.S. ALMA is a partnership of ESO (representing its member states), NSF (USA), and NINS (Japan), together with NRC (Canada) and NSC and ASIAA (Taiwan), in cooperation with the Republic of Chile. The Joint ALMA Observatory is operated by ESO, AUI/NRAO, and NAOJ. This research has made extensive use of the NASA/ IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

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Submitted - 1404.1402.pdf

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August 22, 2023
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