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|Title:||SUDARE-VOICE variability-selection of active galaxies in the Chandra Deep Field South and the SERVS/SWIRE region||Authors:||Falocco, S.
De Cicco, D.
BOTTICELLA, MARIA TERESA
NAPOLITANO, NICOLA ROSARIO
Brandt, W. N.
|Issue Date:||2015||Journal:||ASTRONOMY & ASTROPHYSICS||Number:||579||First Page:||1||Abstract:||Context. One of the most peculiar characteristics of active galactic nuclei (AGNs) is their variability over all wavelengths. This property has been used in the past to select AGN samples and is foreseen to be one of the detection techniques applied in future multi-epoch surveys, complementing photometric and spectroscopic methods. <BR /> Aims: In this paper, we aim to construct and characterise an AGN sample using a multi-epoch dataset in the r band from the SUDARE-VOICE survey. <BR /> Methods: Our work makes use of the VST monitoring programme of an area surrounding the Chandra Deep Field South to select variable sources. We use data spanning a six-month period over an area of 2 square degrees, to identify AGN based on their photometric variability. <BR /> Results: The selected sample includes 175 AGN candidates with magnitude r< 23 mag. We distinguish different classes of variable sources through their lightcurves, as well as X-ray, spectroscopic, SED, optical, and IR information overlapping with our survey. <BR /> Conclusions: We find that 12% of the sample (21/175) is represented by supernovae (SN). Of the remaining sources, 4% (6/154) are stars, while 66% (102/154) are likely AGNs based on the available diagnostics. We estimate an upper limit to the contamination of the variability selected AGN sample ≃34%, but we point out that restricting the analysis to the sources with available multi-wavelength ancillary information, the purity of our sample is close to 80% (102 AGN out of 128 non-SN sources with multi-wavelength diagnostics). Our work thus confirms the efficiency of the variability selection method, in agreement with our previous work on the COSMOS field. In addition we show that the variability approach is roughly consistent with the infrared selection.||Acknowledgments:||We acknowledge the Department of Physics of the University Federico II Naples, Italy. G.L. and E.C. acknowledge the financial support by PRIN 2011 “Cosmology with Euclid Mission”. We acknowledge PRIN INAF 2011 “Galaxy evolution with VST”; we also acknowledge the support from PRIN 2014 (P.I. N. Napolitano). This work was supported by the European Commission Research Executive Agency FP7-SPACE-2013-1 Scheme (Grant Agreement 607254 Herschel Extragalactic Legacy Project - HELP) and by the Italian Ministry for Foreign Affairs and International Cooperation Joint Research Projects of Particular Relevance (Grant Agreement ZA14GR02 - “Mapping the Universe on the Pathway to SKA”). The authors acknowledge L. Greggio for support at OmegaCAM. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III web site is http://www.sdss3.org/ . SDSS-III is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS-III Collaboration including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, University of Portsmouth, Princeton University, the Spanish Participation Group, University of Tokyo, University of Utah, Vanderbilt University, University of Virginia, University of Washington, and Yale University. G.P. acknowledges support provided by the Millennium Institute of Astrophysics (MAS) through grant IC120009 of the Programa Iniciativa Cientifica Milenio del Ministerio de Economia, Fomento y Turismo de Chile. We thank the anonymous referee for constructive comments that were helpful for improving the paper.||URI:||http://hdl.handle.net/20.500.12386/23582||URL:||https://www.aanda.org/articles/aa/abs/2015/07/aa25111-14/aa25111-14.html||ISSN:||0004-6361||DOI:||10.1051/0004-6361/201425111||Bibcode ADS:||2015A&A...579A.115F||Fulltext:||open|
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