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Discovery of a Small Central Disk of CO and H I in the Merger Remnant NGC 34

Fernández, Ximena and Petric, A. O. and Schweizer, François and Van Gorkom, J. H. (2014) Discovery of a Small Central Disk of CO and H I in the Merger Remnant NGC 34. Astronomical Journal, 147 (4). Art. No. 74. ISSN 0004-6256. doi:10.1088/0004-6256/147/4/74.

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We present CO(1-0) and H I (21 cm) observations of the central region of the wet merger remnant NGC 34. The Combined Array for Research in Millimeter-wave Astronomy observations detect a regularly rotating disk in CO with a diameter of 2.1 kpc and a total molecular hydrogen mass of (2.1 ± 0.2) × 10^9 M_☉. The rotation curve of this gas disk rises steeply, reaching maximum velocities at 1'' (410 pc) from the center. Interestingly, H I observations performed with the Karl G. Jansky Very Large Array show that the absorption against the central continuum has the exact same velocity range as the CO in emission. This strongly suggests that the absorbing H I also lies within 1'' from the center, is mixed in, and corotates with the molecular gas. A comparison of H I absorption profiles taken at different resolutions (5''-45'') shows that the spectra at lower resolutions are less deep at the systemic velocity. This provides evidence for H I emission in the larger beams, covering the region from 1 kpc to 9 kpc from the center. The central rapidly rotating disk was likely formed either during the merger or from fall-back material. Lastly, the radio continuum flux of the central source at mm wavelengths (5.4 ± 1.8 mJy) is significantly higher than expected from an extrapolation of the synchrotron spectrum, indicating the contribution of thermal free-free emission from the central starburst.

Item Type:Article
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Petric, A. O.0000-0003-4030-3455
Additional Information:© 2014 American Astronomical Society. Received 2013 October 4; accepted 2014 January 8; published 2014 February 27. Support for CARMA construction was derived from the Gordon and Betty Moore Foundation, the Kenneth T. and Eileen L. Norris Foundation, the James S. McDonnell Foundation, the Associates of the California Institute of Technology, the University of Chicago, the states of California, Illinois, and Maryland, and the National Science Foundation. Ongoing CARMA development and operations are supported by the National Science Foundation under a cooperative agreement, and by the CARMA partner universities. This work was partially supported by NSF grant No. 1009476 to Columbia University.
Funding AgencyGrant Number
Gordon and Betty Moore FoundationUNSPECIFIED
Kenneth T. and Eileen L. Norris FoundationUNSPECIFIED
James S. McDonnell FoundationUNSPECIFIED
Caltech AssociatesUNSPECIFIED
University of ChicagoUNSPECIFIED
states of California, Illinois, and MarylandUNSPECIFIED
NSF Cooperative AgreementUNSPECIFIED
CARMA Partner UniversitiesUNSPECIFIED
Subject Keywords: galaxies: evolution; galaxies: individual (NGC 34, NGC 17, Mrk 938); galaxies: interactions; galaxies: Seyfert; galaxies: starburst; radio continuum: galaxies
Issue or Number:4
Record Number:CaltechAUTHORS:20140501-111620238
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Official Citation: Discovery of a Small Central Disk of CO and H I in the Merger Remnant NGC 34 Ximena Fernández et al. 2014 The Astronomical Journal 147 74
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:45418
Deposited By: Ruth Sustaita
Deposited On:01 May 2014 20:28
Last Modified:10 Nov 2021 17:03

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