Discovery of a z = 4.93, X-ray-selected quasar by the Chandra Multiwavelength Project (ChaMP)

John D. Silverman, Paul J. Green, Dong Woo Kim, Belinda J. Wilkes, Robert A. Cameron, David Morris, Anil Dosaj, Chris Smith, Leopoldo Infante, Paul S Smith, Buell T. Jannuzi, Smita Mathur

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


We present X-ray and optical observations of CXOMP J213945.0-234655, a high-redshift (z = 4.93) quasar discovered through the Chandra Multiwavelength Project (ChaMP). This object is the most distant X-ray-selected quasar published, with a rest-frame X-ray luminosity of Lx = 5.9 × 1044 ergs s-1 (measured in the 0.3-2.5 keV band and corrected for Galactic absorption). CXOMP J213945.0-234655 is a g′ dropout object (>26.2), with r′ = 22.87 and i′ = 21.36. The rest-frame X-ray-to-optical flux ratio is similar to quasars at lower redshifts and slightly X-ray bright relative to z >4 optically selected quasars observed with Chandra. The ChaMP is beginning to acquire significant numbers of high-redshift quasars to investigate the X-ray luminosity function out to z ∼5.

Original languageEnglish (US)
Pages (from-to)L1-L4
JournalAstrophysical Journal
Issue number1 II
StatePublished - Apr 10 2002


  • Galaxies: active
  • Galaxies: nuclei
  • Quasars: general
  • Quasars: individual (CXOMP J213945.0-234655)
  • X-rays: general

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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