The discovery of a luminous z = 5.80 quasar from the sloan digital sky survey

Fan Xiaohui, Richard L. White, Marc Davis, Robert H. Becker, Michael A. Strauss, Zoltan Haiman, Donald P. Schneider, Michael D. Gregg, James E. Gunn, G. R. Knapp, Robert H. Lupton, John E. Anderson, Scott F. Anderson, James Annis, Neta A. Bahcall, William N. Boroski, Robert J. Brunner, Bing Chen, Andrew J. Connolly, István CsabaiDoi Mamoru, Masataka Fukugita, G. S. Hennessy, Robert B. Hindsley, Takashi Ichikawa, Eljko Ivezić, Jon Loveday, Avery Meiksin, Timothy A. Mckay, Jeffrey A. Munn, Heidi Jo Newberg, Robert Nichol, Sadanori Okamura, Jeffrey R. Pier, Maki Sekiguchi, Kazuhiro Shimasaku, Chris Stoughton, Alexander S. Szalay, Gyula P. Szokoly, Aniruddha R. Thakar, Michael S. Vogeley, Donald G. York

Research output: Contribution to journalReview articlepeer-review

243 Scopus citations


We present observations of SDSSp J104433.04-012502.2, a luminous quasar at z = 5.80 discovered from Sloan Digital Sky Survey (SDSS) multicolor imaging data. This object was selected as an i′-band dropout object, with i* = 21.8 ± 0.2 and z* = 19.2 ± 0.1. It has an absolute magnitude M1450 = -27.2 (H0 = 50 km s-1 Mpc-1, q0 = 0.5). The spectrum shows a strong and broad Lyα emission line, strong Lyα forest absorption lines with a mean continuum decrement DA = 0.91 and a Lyman limit system at z = 5.72. The spectrum also shows strong O I and Si IV emission lines similar to those of quasars at z ≲ 5, suggesting that these metals were produced at a redshift beyond 6. The lack of a Gunn-Peterson trough in the spectrum indicates that the universe is already highly ionized at z ∼ 5.8. Using a high-resolution spectrum in the Lyα forest region, we place a conservative upper limit on the optical depth because of the Gunn-Peterson effect of τ < < 0.5 in regions of minimum absorption. The Lyα forest absorption in this object is much stronger than that in quasars at z ≲ 5. The object is unresolved in a deep image with excellent seeing, implying that it is unlensed. The black hole mass of this quasar is ∼3 × 109 M if we assume no lensing amplification and that it is radiating at the Eddington luminosity, implying that it resides in a very massive dark matter halo. The discovery of one quasar at M1450 < -27 in a survey area of 600 deg2 is consistent with an extrapolation of the observed luminosity function at lower redshifts. The abundance and evolution of such quasars can provide sensitive tests for models of quasar and galaxy formation.

Original languageEnglish (US)
Pages (from-to)1167-1174
Number of pages8
JournalAstronomical Journal
Issue number3
StatePublished - Sep 2000


  • Intergalactic medium
  • Quasars: absorption lines
  • Quasars: emission lines
  • Quasars: individual (SDSSp J104433.04-012502.2)

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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