Constraining the Evolution of the Ionizing Background and the Epoch of Reionization with z  ~ 6 Quasars. II. A Sample of 19 Quasars

We study the evolution of the ionization state of the intergalactic medium (IGM) at the end of the reionization epoch using moderate resolution spectra of a sample of nineteen quasars at 5.74 < z{sub em} < 6.42 discovered in the Sloan Digital Sky Survey. Three methods are used to trace IGM properties: (a) the evolution of the Gunn-Peterson (GP) optical depth in the Ly{alpha}, {beta}, and {gamma} transitions; (b) the distribution of lengths of dark absorption gaps, and (c) the size of HII regions around luminous quasars. Using this large sample, we find that the evolution of the ionization state of the IGM accelerated at z > 5.7: the GP optical depth evolution changes from {tau}{sub GP}{sup eff}…

• NS
  National Science Foundation
• SI
  Smithsonian Institution
• UD
  U.S. Department of Energy
• NA
  National Aeronautics and Space Administration
• AP
  Alfred P. Sloan Foundation
• WM
  W. M. Keck Foundation
• PU
  Princeton University
• CI
  California Institute of Technology
• UO
  University of Washington
• JH
  Johns Hopkins University
• UO
  University of Pittsburgh
• UO
  University of Portsmouth
• NM
  New Mexico State University
• M
  Max-Planck-Gesellschaft
• MF
  Max-Planck-Institut für Astronomie
• KI
  Kavli Institute for Theoretical Physics, University of California, Santa Barbara
• UN
  U.S. Naval Observatory
• F
  Fermilab
• LA
  Los Alamos National Laboratory