2006/05/01 by Richard J. Cool, Christopher S. Kochanek, C. S. Kochanek +22 · 63 citations
Physics and Astronomy · #Astronomy #Astrophysics #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Luminosity #Luminosity function #OVV quasar #Physics #Quasar #Redshift #Redshift survey #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/505535
published in The Astronomical Journal 132(2), 823-830 (Institute of Physics) · 9 page, 7 figures. Accepted for publication in AJ
arxiv created 2006/05/01 · openalex publication_date 2006/07/07 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We present the discovery of three z > 5 quasars in the AGN and Galaxy Evolution Survey spectroscopic observations of the NOAO Deep Wide-Field Survey (NDWFS) Bootes Field. These quasars were selected as part of a larger Spitzer mid-infrared quasar sample, with no selection based on optical colors. The highest redshift object, NDWFS J142516.3+325409, at z = 5.85, is the lowest luminosity z > 5.8 quasar currently known. We compare mid-infrared techniques for identifying z > 5 quasars to more traditional optical techniques and show that mid-infrared colors allow for the selection of high-redshift quasars even at redshifts at which quasars lie near the optical stellar locus and at z > 7, where optical selection is impossible. Using the superb multiwavelength coverage available in the NDWFS Bootes field, we construct the spectral energy distributions (SEDs) of high-redshift quasars from observed B W band to 24 μm (rest-frame 600 Å-3.7 μm). We show that the three high-redshift quasars have quite similar SEDs, and the rest-frame composite SED of low-redshift quasars from the literature shows little evolution compared to our high-redshift objects. We compare the number of z > 5 quasars we have discovered to the expected number from published quasar luminosity functions. While analyses of the quasar luminosity function are tenuous based on only three objects, we find that a relatively steep luminosity function with Ψ ∝ L -3.2 provides the best agreement with the number of high-redshift quasars discovered in our survey.