Evidence for a large fraction of Compton-thick quasars at high redshift

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dc.creatorMartinez-Sansigre, Alejo
dc.creatorRawlings, Steve
dc.creatorBonfield, David G.
dc.creatorMateos, Silvia
dc.creatorSimpson, Chris
dc.creatorWatson, Mike
dc.creatorAlmaini, Omar
dc.creatorFoucaud, Sebastien
dc.creatorSekiguchi, Kazuhiro
dc.creatorUeda, Yoshihiro
dc.date2006-11-23
dc.date2007-05-14
dc.date.accessioned2026-07-07T10:36:37Z
dc.date.available2026-07-07T10:36:37Z
dc.descriptionUsing mid-infrared and radio selection criteria, we pre-select a sample of candidate high-redshift type-2 quasars in the Subaru XMM-Newton Deep Field (SXDF). To filter out starburst contaminants, we use a bayesian method to fit the spectral energy distributions (SEDs) between 24-microns and B-band, obtain photometric redshifts, and identify the best candidates for high-z type-2 quasars. This leaves us with 12 z_phot >= 1.7 type-2 quasar candidates in an area ~0.8 deg^2, of which only two have secure X-ray detections. The two detected sources have estimated column densities N_H~2 & 3x10^27 m^-2, i.e. heavily obscured but Compton-thin quasars. Given the large bolometric luminosities and redshifts of the undetected objects, the lack of X-ray detections suggests extreme absorbing columns N_H >= 10^28 m^-2 are typical. We have found evidence for a population of ``Compton-thick'' high-redshift type-2 quasars, at least comparable to, and probably larger than the type-1 quasar population, although spectroscopic confirmation of their AGN nature is important.
dc.description6 pages, 2 colour figures. Accepted by MNRAS. Full resolution version and supplementary figures can be found at: http://www.mpia.de/homes/martinez/publications.html
dc.identifierhttps://arxiv.org/abs/astro-ph/0611739
dc.identifierhttp://arxiv.org/abs/astro-ph/0611739
dc.identifierMon.Not.Roy.Astron.Soc.Lett.379:L6-L10,2007
dc.identifierdoi:10.1111/j.1745-3933.2007.00323.x
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/180117
dc.subjectAstrophysics
dc.titleEvidence for a large fraction of Compton-thick quasars at high redshift
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