A snapshot survey for gravitational lenses among z >= 4.0 quasars. II. Constraints on the 4.0 < z < 5.4 quasar population
GT Richards, Z Haiman, B Pindor, MA Strauss, XH Fan, D Eisenstein, DP Schneider, NA Bahcall, J Brinkmann, M Fukugita
ASTRONOMICAL JOURNAL | IOP PUBLISHING LTD | Published : 2006
We report on i-band snapshot observations of 157 Sloan Digital Sky Survey quasars at 4.0 < z -3.8(3 σ), assuming a break in the quasar luminosity function at M* 1450 ∼ -24.5. This constraint is considerably stronger than the limit of β > -4.63 obtained from the absence of lensing in four z > 5.7 quasars. Such constraints are important to our understanding of the true space density of high-redshift quasars and the ionization state of the early universe. © 2006. The American Astronomical Society. All rights reserved.