2006/11/30 by Alejo Martínez‐Sansigre, Alejo Martinez-Sansigre, Steve Rawlings +13 · 1 citation
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #OVV quasar #Physics #Population #Quasar #Redshift #astro-ph
paper · pdf · doi:10.1111/j.1745-3933.2007.00323.x
published as Mon.Not.Roy.Astron.Soc.Lett.379:L6-L10,2007 · 6 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
arxiv created 2007/05/14 · openalex publication_date 2007/06/06 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Abstract Using 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-μm and the B-band, obtain photometric redshifts, and identify the best candidates for high-z type 2 quasars. This leaves us with 12 zphot≥ 1.7 type 2 quasar candidates in an area ∼0.8 deg2, of which only two have secure X-ray detections. The two detected sources have estimated column densities NH∼ 2 & 3 × 1027 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 NH≳ 1028 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 active galactic nuclei nature is important.