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Title: A multi-wavelength survey of AGN in the XMM-LSS field I. Quasar selection via the KX technique
Authors: Nakos, T.
Willis, J. P.
Andreon, S.
Surdej, J.
Riaud, P.
Hatziminaoglou, E.
Garcet, O.
Alloin, D.
Baes, M.
Galaz, G.
Pierre, M.
Quintana, H.
Page, M. J.
Tedds, Jonathan A.
Ceballos, M. T.
Corral, A.
Ebrero, J.
Krumpe, M.
Mateos, S.
First Published: 22-Dec-2008
Publisher: EDP Sciences for European Southern Observatory (ESO)
Citation: Astronomy and Astrophysics, 2009, 494 (2), pp. 579-589
Abstract: Aims. We present a sample of candidate quasars selected using the KX-technique. The data cover 0.68 deg2 of the X-ray Multi-Mirror (XMM) Large-Scale Structure (LSS) survey area where overlapping multi-wavelength imaging data permits an investigation of the physical nature of selected sources. Methods. The KX method identifies quasars on the basis of their optical (R and z') to near-infrared $(K_{\rm s})$ photometry and point-like morphology. We combine these data with optical (u*,g', r',i',z') and mid-infrared (3.6-24  $\mu$m) wavebands to reconstruct the spectral energy distributions (SEDs) of candidate quasars. Results. Of 93 sources selected as candidate quasars by the KX method, 25 are classified as quasars by the subsequent SED analysis. Spectroscopic observations are available for 12/25 of these sources and confirm the quasar hypothesis in each case. Even more, 90% of the SED-classified quasars show X-ray emission, a property not shared by any of the false candidates in the KX-selected sample. Applying a photometric redshift analysis to the sources without spectroscopy indicates that the 25 sources classified as quasars occupy the interval 0.7 $\le$ z $\le$ 2.5. The remaining 68/93 sources are classified as stars and unresolved galaxies.
DOI Link: 10.1051/0004-6361:200809584
ISSN: 0004-6361
eISSN: 1432-0746
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2009, ESO. Deposited with reference to the publisher’s open access archiving policy.
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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