@article{10902/4116,
year = {2013},
month = {7},
url = {http://hdl.handle.net/10902/4116},
abstract = {Mateos et al. presented a highly reliable and efficient mid-infrared (MIR) colour-based selection technique for luminous active galactic nuclei (AGN) using the Wide-field Infrared Survey Explorer (WISE) survey. Here, we evaluate the effectiveness of this technique to identify obscured AGN missed in X-ray surveys. To do so we study the WISE properties of AGN independently selected in hard X-ray and optical surveys. We use the largest catalogue of 887 [OIII] λ5007-selected type 2 quasars (QSO2s) at z ≤ 0.83 in the literature from the Sloan Digital Sky Survey (SDSS), and the 258 hard (>4.5 keV) X-ray-selected AGN from the Bright Ultrahard XMM–Newton Survey (BUXS). The fraction of SDSS QSO2s in our infrared AGN selection region (wedge) increases with the AGN luminosity, reaching 66.1+4.5−4.7 per cent at the highest [OIII] luminosities in the sample. This fraction is substantially lower than for the BUXS type 1 AGN (96.1+3.0−6.3 per cent), but consistent, within the uncertainties, with that for the BUXS type 2 AGN (75.0+14.1−19.1 per cent) with the same luminosity. The SDSS QSO2s appear to reside in more luminous (massive) hosts than the BUXS AGN, due to the tight magnitude limits applied in the SDSS spectroscopic target selection. Since host galaxy dilution can reduce substantially the effectiveness of MIR-based techniques, this may explain the lower fraction of SDSS QSO2s in the WISE AGN wedge. The fraction of SDSS QSO2s identified as Compton-thick candidates that fall in the wedge is consistent with the fraction of all SDSS QSO2s in that zone. At the AGN luminosities involved in the comparison, Compton-thick and Compton-thin SDSS QSO2s have similar WISE colour distributions. We conclude that at high luminosities and z ≤ 1 our MIR technique is very effective at identifying both Compton-thin and Compton-thick AGN.},
organization = {This work is based on observations obtained with XMM–Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA. Based on data from the Wide-field Infrared Survey Explorer, which is a joint project of the University of California, Los Angeles, and the Jet Propulsion Laboratory/California Institute of Technology, funded by the National Aeronautics and Space Administration. Funding for the SDSS and SDSS-II has been provided by the Alfred P. Sloan Foundation, the Participating Institutions, the National Science Foundation, the U.S. Department of Energy, the National Aeronautics and Space Administration, the Japanese Monbukagakusho, the Max Planck Society and the Higher Education Funding Council for England. The SDSS Web Site is http://www.sdss.org/. Based on observations collected at the European Organization for Astronomical Research in the Southern hemisphere, Chile, programme IDs 084.A-0828, 086.A0612, 087.A-0447 and 088.A-0628. Based on observations made with the William Herschel Telescope and its service programme – operated by the Isaac Newton Group, the Telescopio Nazionale Galileo – operated by the Centro Galileo Galilei and the Gran Telescopio de Canarias installed in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofsica de Canarias, in the island of La Palma. SM and FJC acknowledge financial support by the Spanish Ministry of Economy and Competitiveness through grant AYA2010-21490-C02-01. SM, FJC and A.A.-H. acknowledge financial support by the Spanish Ministry of Economy and Competitiveness through grant AYA2012-31447. SM, FJC and A.A.- H. acknowledge financial support from the ARCHES project (7th Framework of the European Union, No. 313146). SM acknowledges financial support from the JAE-Doc program (Consejo Superior de Investigaciones Cientficas, cofunded by FSE). AA-H acknowledges support from the Universidad de Cantabria through the Augusto G. Linares program. AB acknowledges a Royal Society Wolfson Research Merit Award. PS acknowledges financial support from ASI (grant No. I/009/10/0). AR acknowledges support from an IUCAA post-doctoral fellowship. The authors thank A. Hernan Caballero ´ for useful suggestions. The authors wish to thank the anonymous referee for constructive comments.},
publisher = {Royal Astronomical Society},
publisher = {Monthly Notices of the Royal Astronomical Society, 2013, 434(2), 941-955},
title = {Uncovering obscured luminous AGN with WISE},
author = {Mateos Ibáñez, Silvia and Alonso Herrero, Almudena and Carrera Troyano, Francisco Jesús and Blain, Andrew W. and Severgnini, Paola and Caccianiga, Alessandro and Ruiz Camuñas, Ángel},
}