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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 421623.0, MPI für Astronomie / Publikationen_mpia
A survey of z ~ 6 quasars in the Sloan Digital Sky Survey Deep Stripe. I. a Flux-Limited Sample at zAB < 21
Authors:Jiang, Linhua; Fan, Xiaohui; Annis, James; Becker, Robert H.; White, Richard L.; Chiu, Kuenley; Lin, Huan; Lupton, Robert H.; Richards, Gordon T.; Strauss, Michael A.; Jester, Sebastian; Schneider, Donald P.
Language:English
Date of Publication (YYYY-MM-DD):2008
Title of Journal:The Astronomical Journal
Volume:135
Start Page:1057
End Page:1066
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:We present the discovery of five quasars at z ~ 6 selected from 260 deg2 of the Sloan Digital Sky Survey (SDSS) southern survey, a deep imaging survey obtained by repeatedly scanning a stripe along the celestial equator. The five quasars with 20 < zAB < 21 are 1-2 magnitudes fainter than the luminous z ~ 6 quasars discovered in the SDSS main survey. One of them was independently discovered by the UKIRT Infrared Deep Sky Survey. These quasars, combined with another z ~ 6 quasar known in this region, make a complete flux-limited quasar sample at zAB < 21. The sample spans the redshift range 5.85 <= z <= 6.12 and the luminosity range 26.5 <= M 1450 <= 25.4 (H 0 = 70 km s 1 Mpc 1, Omega m = 0.3, and OmegaLambda = 0.7). We use the 1/Va method to determine that the comoving quasar spatial density at langzrang = 6.0 and langM 1450rang = 25.8 is (5.0 ± 2.1) × 10 9 Mpc 3 mag 1. We model the bright-end quasar luminosity function (QLF) at z ~ 6 as a power law Phi(L 1450) vprop L beta 1450. The slope beta calculated from a combination of our sample and the luminous SDSS quasar sample is 3.1 ± 0.4, significantly steeper than the slope of the QLF at z ~ 4. Based on the derived QLF, we find that the quasar/active galactic nucleus (AGN) population cannot provide enough photons to ionize the intergalactic medium (IGM) at z ~ 6 unless the IGM is very homogeneous and the luminosity (L*1450) at which the QLF power law breaks is very low. Based on observations obtained with the Sloan Digital Sky Survey, which is owned and operated by the Astrophysical Research Consortium; the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution; the 6.5 m Magellan Telescopes located at Las Campanas Observatory, Chile; the W.M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California and the National Aeronautics and Space Administration, and was made possible by the generous financial support of the W.M. Keck Foundation.
Free Keywords:galaxies: active; quasars: emission lines; quasars: general
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2008AJ....135.1057J [ID No:1]
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