Discovery of a pair of z = 4.25 quasars from the Sloan Digital Sky Survey

Donald P. Schneider, Xiaohui Fan, Michael A. Strauss, James E. Gunn, Gordon T. Richards, G. R. Knapp, Robert H. Lupton, David H. Saxe, John E. Anderson, Neta A. Bahcall, J. Brinkmann, Robert Brunner, István Csabai, Masataka Fukugita, G. S. Hennessy, Robert B. Hindsley, Željko Ivezić, R. C. Nichol, Jeffrey R. Pier, Donald G. York

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20 Citations (Scopus)


We report the discovery of a pair of z = 4.25 quasars with a separation of 33″. The brighter of the two objects was identified as a high-redshift quasar candidate from Sloan Digital Sky Survey multicolor imaging data, and the redshift was measured from a spectrum obtained with the Hobby-Eberly Telescope. The slit orientation of this observation by chance included another quasar, approximately 1 mag fainter and having the same redshift as the target. This is the third serendipitous discovery of a z > 4 quasar. The differences in the relative strengths and profiles of the emission lines suggest that this is a quasar pair and not a gravitational lens. The two objects are likely to be physically associated; the projected physical separation is approximately 210 h-150 kpc and the redshifts are identical to ≈0.01, implying a radial physical separation of 950 h-150 kpc or less. The existence of this pair is strong circumstantial evidence that z ∼ 4 quasars are clustered.

Original languageEnglish
Pages (from-to)2183-2189
Number of pages7
JournalAstronomical Journal
Issue number5
Publication statusPublished - Nov 2000



  • Early universe
  • Quasars: individual

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

Cite this

Schneider, D. P., Fan, X., Strauss, M. A., Gunn, J. E., Richards, G. T., Knapp, G. R., Lupton, R. H., Saxe, D. H., Anderson, J. E., Bahcall, N. A., Brinkmann, J., Brunner, R., Csabai, I., Fukugita, M., Hennessy, G. S., Hindsley, R. B., Ivezić, Ž., Nichol, R. C., Pier, J. R., & York, D. G. (2000). Discovery of a pair of z = 4.25 quasars from the Sloan Digital Sky Survey. Astronomical Journal, 120(5), 2183-2189.