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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
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Abstract

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.

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A. C. Fabian, A. Celotti, G. Pooley, K. Iwasawa, W. N. Brandt, R. G. McMahon, M. D. Hoenig. 1999-07-02. Variability of the extreme z=4.72 blazar, GB 1428+4217. https://doi.org/10.1046/j.1365-8711.1999.02910.x

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