The sloan digital sky survey quasar survey: Quasar luminosity function from data release 3

Gordon T. Richards, Michael A. Strauss, Xiaohui Fan, Patrick B. Hall, Sebastian Jester, Donald P. Schneider, Daniel E. Vanden Berk, Chris Stoughton, Scott F. Anderson, Robert J. Brunner, Jim Gray, James E. Gunn, Želfko Ivezić, Margaret K. Kirkland, G. R. Knapp, Jon Loveday, Avery Meiksin, Adrian Pope, Alexander S. Szalay, Anirudda R. ThakarBrian Yanny, Donald G. York, J. C. Barentine, Howard J. Brewington, J. Brinkmann, Masataka Fukugita, Michael Harvanek, Stephen M. Kent, S. J. Kleinman, Jurek Krzesiński, Daniel C. Long, Robert H. Lupton, Thomas Nash, Eric H. Neilsen, Atsuko Nitta, David J. Schlegel, Stephanie A. Snedden

Research output: Contribution to journalArticlepeer-review


We determine the number counts and z = 0-5 luminosity function for a well-defined, homogeneous sample of quasars from the Sloan Digital Sky Survey (SDSS). We conservatively define the most uniform statistical sample possible, consisting of 15,343 quasars within an effective area of 1622 deg 2 that was derived from a parent sample of 46,420 spectroscopically confirmed broad-line quasars in the 5282 deg 2 of imaging data from SDSS Data Release 3. The sample extends from i = 15 to 19.1 at z ≲ 3 and to i = 20.2 for z ≳ 3. The number counts and luminosity function agree well with the results of the Two Degree Field QSO Redshift Survey (2QZ) at redshifts and luminosities at which the SDSS and 2QZ quasar samples overlap, but the SDSS data probe to much higher redshifts than does the 2QZ sample. The number density of luminous quasars peaks between redshifts 2 and 3, although uncertainties in the selection function in this range do not allow us to determine the peak redshift more precisely. Our best-fit model has a flatter bright-end slope at high redshift than at low redshift. For z < 2.4 the data are best fit by a redshift-independent slope of β = -3.1 [Φ(L) ∝ L β]. Above z = 2.4 the slope flattens with redshift to β ≳ - 2.37 at z = 5. This slope change, which is significant at the ≳ 5 σ level, must be accounted for in models of the evolution of accretion onto supermassive black holes.

Original languageEnglish (US)
Pages (from-to)2766-2787
Number of pages22
JournalAstronomical Journal
Issue number6
StatePublished - Jun 2006


  • Cosmology: observations
  • Galaxies: active
  • Galaxies: luminosity function, mass function quasars: general
  • Surveys

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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