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Bizarre Hard X-ray Outbursts of Cygnus X-1

Boris E. Stern·Andrei M. Beloborodov·Juri Poutanen
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Abstract

A very high activity of Cygnus X-1 on 1999 April 19-21 was recorded by BATSE Large Area Detectors onboard the Compton Gamma-Ray Observatory. The peak luminosity was one order of magnitude higher than the normal luminosity of Cyg X-1. This fact can be critical for models of the hard state of Cyg X-1. The longest outburst lasted ~1000 s and demonstrated very unusual temporal and spectral behavior which indicates the presence of two emission components. One component is relatively soft (with a cutoff below 100 keV) and highly variable, and the other one is hard (extending above 100 keV), with much slower variability.

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Boris E. Stern, Andrei M. Beloborodov, Juri Poutanen. 2001-03-09. Bizarre Hard X-ray Outbursts of Cygnus X-1. https://doi.org/10.1086/321462

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