Norris, Ray P. and Afonso, Jose and Cava, Antonio and Farrah, Duncan and Huynh, Minh T. and Ivison, R. J. and Jarvis, Matt and Lacy, Mark and Mao, Minnie and Maraston, Claudia and Mauduit, Jean-Christophe and Middelberg, Enno and Oliver, Seb and Seymour, Nick and Surace, Jason (2011) Deep Spitzer Observations of Infrared-faint Radio Sources: High-redshift Radio-loud Active Galactic Nuclei? Astrophysical Journal, 736 (1). Art. No. 55. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20110801-133216892
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Infrared-faint radio sources (IFRSs) are a rare class of objects which are relatively bright at radio wavelengths but very faint at infrared and optical wavelengths. Here we present sensitive near-infrared observations of a sample of these sources taken as part of the Spitzer Extragalactic Representative Volume Survey. Nearly all the IFRSs are undetected at a level of ~1 μJy in these new deep observations, and even the detections are consistent with confusion with unrelated galaxies. A stacked image implies that the median flux density is S_(3.6 μm) ~ 0.2 μJy or less, giving extreme values of the radio-infrared flux density ratio. Comparison of these objects with known classes of object suggests that the majority are probably high-redshift radio-loud galaxies, possibly suffering from significant dust extinction.
|Additional Information:||© 2011 American Astronomical Society. Received 2010 April 6; accepted 2011 May 4; published 2011 July 6. This work is based in part on observations made with Spitzer, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. Support for this work was provided by NASA through an award issued by JPL/Caltech. This research has made 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. The Australia Telescope is funded by the Commonwealth of Australia for operation as a National Facility managed by CSIRO. J.A. gratefully acknowledges the support from the Science and Technology Foundation (FCT, Portugal) through the research grant PTDC/FIS/100170/2008. M.Y.M. acknowledges the support of an Australian Postgraduate Award as well as Postgraduate Scholarships from AAO and ATNF. We thank P. Barmby for providing unpublished details of her source density calculations, Barnaby Norris for generating the stacked median image, and George Hobbs for helpful comments on the pulsar density at high galactic latitude.|
|Subject Keywords:||galaxies: evolution; galaxies: formation; galaxies: starburst|
|Classification Code:||PACS: 98.54.Cm, 95.85.Jq, 98.62.Py, 98.70.Dk|
|Official Citation:||Deep Spitzer Observations of Infrared-faint Radio Sources: High-redshift Radio-loud Active Galactic Nuclei? Ray P. Norris et al. 2011 ApJ 736 55|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Jason Perez|
|Deposited On:||01 Aug 2011 22:29|
|Last Modified:||26 Dec 2012 13:26|
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