2003/01/08 by Xiaohui Fan, Michael A. Strauss, Donald P. Schneider +37 · 33 citations
Physics and Astronomy · #Astrophysical Phenomena and Observations #Galaxies: Formation, Evolution, Phenomena #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/368246
published as Astron.J.125:1649,2003 · AJ in press (Apr 2003), 26 pages, 9 figures
arxiv created 2003/01/08 · openalex publication_date 2003/03/25 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/01
We present the discovery of three new quasars at z > 6 in ∼ 1300 deg 2 of Sloan Digital Sky Survey imaging data, J114816.64+525150.3 ( z = 6.43), J104845.05+463718.3 ( z = 6.23), and J163033.90+401209.6 ( z = 6.05). The first two objects have weak Lyα emission lines; their redshifts are determined from the positions of the Lyman break. They are only accurate to ∼0.05 and could be affected by the presence of broad absorption line systems. The last object has a Lyα strength more typical of lower redshift quasars. Based on a sample of six quasars at z > 5.7 that cover 2870 deg 2 presented in this paper and in Paper I, we estimate the comoving density of luminous quasars at z ∼ 6 and M 1450 < -26.8 to be (8 ± 3) × 10 -10 Mpc -3 (for H 0 = 50 km s -1 Mpc -1 , Ω = 1). Hubble Space Telescope imaging of two z > 5.7 quasars and high-resolution, ground-based images (seeing ∼0 4) of three additional z > 5.7 quasars show that none of them is gravitationally lensed. The luminosity distribution of the high-redshift quasar sample suggests the bright-end slope of the quasar luminosity function at z ∼ 6 is shallower than Ψ ∝ L -3.5 (2 σ), consistent with the absence of strongly lensed objects.