2005/03/24 by Jane R. Rigby, J. R. Rigby, G. H. Rieke +9 · 25 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Luminosity #Luminosity function #Optical spectra #Photometry (optics) #Physics #Redshift #Spectral line #Spectroscopy #Spitzer Space Telescope #Stars #Telescope #astro-ph
paper · pdf · doi:10.1086/430398
published in The Astrophysical Journal 627(1), 134-139 (IOP Publishing) · Accepted for publication in the Astrophysical Journal
arxiv created 2005/03/24 · openalex publication_date 2005/06/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
Optically faint X-ray sources (those with f X / f R > 10) constitute about 20% of X-ray sources in deep surveys and are potentially highly obscured and/or at high redshift. Their faint optical fluxes are generally beyond the reach of spectroscopy. For a sample of 20 optically faint sources in CDFS, we compile 0.4-24 μm photometry, relying heavily on the Spitzer Space Telescope . We estimate photometric redshifts for 17 of these 20 sources. We find that these AGNs are optically faint, both because they lie at significantly higher redshifts (median z ~ 1.6) than most X-ray-selected AGNs, and because their spectra are much redder than standard AGNs. They have 2-8 keV X-ray luminosities in the Seyfert range, unlike the QSO luminosities of optically faint AGNs found in shallow wide-field surveys. Their contribution to the X-ray Seyfert luminosity function is comparable to that of z > 1 optically bright AGNs.