Variability of the extreme z = 4.72 blazar, GB 1428+4217

A. C. Fabian, A. Celotti, G. Pooley, K. Iwasawa, W. N. Brandt, R. G. McMahon, M. D. Hoenig

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


We report X-ray and radio variability of GB 1428+4217 which confirm its blazar nature. IR observations reveal a powerful optical-UV component, not obscured by dust, which is suggestive of the presence of a billion solar mass black hole, already formed by z ∼ 5. A detailed comparison of the broad-band spectral properties of GB 1428+4217 with those of nearby blazars shows it to be extreme, but nevertheless consistent with the trend found for nearby sources.

Original languageEnglish (US)
Pages (from-to)L6-L10
JournalMonthly Notices of the Royal Astronomical Society
Issue number1
StatePublished - Sep 1 1999

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


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