Parra, R. and Conway, J. E. and Aalto, S. and Appleton, P. N. and Norris, R. P. and Pihlström, Y. M. and Kewley, L. J. (2010) COLA. III. Radio Detection of Active Galactic Nucleus in Compact Moderate Luminosity Infrared Galaxies. Astrophysical Journal, 720 (1). pp. 555-568. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20100928-102158506
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We present results from 4.8 GHz Very Large Array (VLA) and global very long baseline interferometry (VLBI) observations of the northern half of the moderate FIR luminosity (median L_(IR) = 10^(11.01) L_☉) COLA sample of star-forming galaxies. VLBI sources are detected in a high fraction (20/90) of the galaxies observed. The radio luminosities of these cores (~10^(21) W Hz^(–1)) are too large to be explained by radio supernovae or supernova remnants and we argue that they are instead powered by active galactic nuclei (AGNs). These sub-parsec scale radio cores are preferentially detected toward galaxies whose VLA maps show bright 100-500 parsec scale nuclear radio components. Since these latter structures tightly follow the FIR to radio-continuum correlation for star formation, we conclude that the AGN-powered VLBI sources are associated with compact nuclear starburst environments. The implications for possible starburst-AGN connections are discussed. The detected VLBI sources have a relatively narrow range of radio luminosity consistent with models in which intense compact Eddington-limited starbursts regulate the gas supply onto a central supermassive black hole. The high incidence of AGN radio cores in compact starbursts suggests little or no delay between the starburst phase and the onset of AGN activity.
|Additional Information:||© 2010 American Astronomical Society. Received 2009 July 31; accepted 2010 June 13; published 2010 August 12. We thank the anonymous referee for his/her very helpful comments on an earlier version of this paper. R.P. acknowledges a Chalmers University PhD student stipend and FONDECYT postdoctoral research grant 3085032. J.C. acknowledges a Swedish VR grant. The European VLBI Network is a joint facility of European, Chinese, South African and other radio astronomy institutes funded by their national research councils. The Arecibo Observatory is the principal facility of the National Astronomy and Ionosphere Center which is operated by Cornell University under a cooperative agreement with the National Science Foundation. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under a cooperative agreement by Associated Universities, Inc. This research has made use of theNASA/IPACExtragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.|
|Subject Keywords:||galaxies: active; galaxies: starburst; infrared: galaxies; radio continuum: galaxies|
|Classification Code:||PACS: 98.54.Cm; 95.85.Bh; 98.58.Mj; 98.70.Dk; 98.54.Ep; 98.62.Js|
|Official Citation:||R. Parra et al 2010 ApJ 720 555 doi: 10.1088/0004-637X/720/1/555|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||29 Sep 2010 21:00|
|Last Modified:||26 Dec 2012 12:28|
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