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The Host Galaxies of Micro-Jansky Radio Sources

Luchsinger, K. M. and Lacy, M. and Jones, K. M. and Mauduit, J. C. and Pforr, J. and Surace, J. A. and Vaccari, M. and Farrah, D. and Gonzales-Solares, E. and Jarvis, M. J. and Maraston, C. and Marchetti, L. and Oliver, S. and Afonso, J. and Cappozi, D. and Sajina, A. (2015) The Host Galaxies of Micro-Jansky Radio Sources. Astronomical Journal, 150 (3). Art. No. 87. ISSN 0004-6256. http://resolver.caltech.edu/CaltechAUTHORS:20151202-082609868

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Abstract

We combine a deep 0.5 deg^2, 1.4 GHz deep radio survey in the Lockman Hole with infrared and optical data in the same field, including the Spitzer Extragalactic Representative Volume Survey (SERVS) and UKIDSS near-infrared surveys, to make the largest study to date of the host galaxies of radio sources with typical radio flux densities ~ 50 μJy. 87% (1274/1467) of radio sources have identifications in SERVS to AB ≈ 23.1 at 3.6 or 4.5μm, and 9% are blended with bright objects (mostly stars), leaving only 4% (59 objects), which are too faint to confidently identify in the near-infrared. We are able to estimate photometric redshifts for 68% of the radio sources. We use mid-infrared diagnostics to show that the source population consists of a mixture of star-forming galaxies, rapidly accreting (cold mode) active galactic nuclei (AGNs) and low accretion rate (hot mode) AGNs, with neither AGNs nor star-forming galaxies clearly dominating. We see the breakdown in the K–z relation in faint radio source samples, and show that it is due to radio source populations becoming dominated by sources with radio luminosities ~ 10^(23) WHz^(-1). At these luminosities, both the star-forming galaxies and the cold mode AGNs have hosts with stellar luminosities of about a factor of two lower than those of hot mode AGNs, which continue to reside in only the most massive hosts. We show that out to at least z ~ 2, galaxies with stellar masses > 10^(11.5) M⊙ have radio-loud fractions up to ~30%. This is consistent with there being a sufficient number of radio sources for radio-mode feedback to play a role in galaxy evolution.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1088/0004-6256/150/3/87DOIArticle
http://iopscience.iop.org/article/10.1088/0004-6256/150/3/87/metaPublisherArticle
http://arxiv.org/abs/1507.01144arXivDiscussion Paper
ORCID:
AuthorORCID
Luchsinger, K. M.0000-0002-2942-6924
Lacy, M.0000-0002-3032-1783
Jones, K. M.0000-0002-8141-0583
Surace, J. A.0000-0001-7291-0087
Vaccari, M.0000-0002-6748-0577
Farrah, D.0000-0003-1748-2010
Maraston, C.0000-0001-7711-3677
Marchetti, L.0000-0003-3948-7621
Oliver, S.0000-0001-7862-1032
Afonso, J.0000-0002-9149-2973
Additional Information:© 2015 The American Astronomical Society. Received 2014 November 16; accepted 2015 June 29; published 2015 August 25. We thank the referee for a careful reading of the manuscript. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. This work made extensive use of topcat (Taylor 2005) for catalog matching and analysis, and the Virtual Observatory SAMP protocol for communication between applications. This paper also made use of the SERVS Lockman data holdings in the Infrared Science Archive, ADS/IRSA.Atlas#2014/1025/091233_11822. J.A. gratefully acknowledges support from the Science and Technology Foundation (FCT, Portugal) through the research grant PTDC/FIS-AST/2194/2012 and PEst-OE/FIS/UI2751/2014.
Group:Infrared Processing and Analysis Center (IPAC)
Funders:
Funding AgencyGrant Number
Fundação para a Ciência e a Tecnologia (FCT)PTDC/FIS-AST/2194/2012
Fundação para a Ciência e a Tecnologia (FCT)PEst-OE/FIS/UI2751/2014
Subject Keywords:galaxies: active – galaxies: evolution – radio continuum: galaxies
Record Number:CaltechAUTHORS:20151202-082609868
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20151202-082609868
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:62530
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:02 Dec 2015 17:33
Last Modified:09 Jul 2019 21:08

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