Time delay of the PeV gamma ray burst after the October 1985 radio flare of Cygnus X-3

Cygnus X-3 remains a puzzling and controversial source of ultra-high-energy radiation, E ≥ 0.1 PeV. In existing data, TeV and sometimes PeV radiation has been seen episodically; such an episode is connected with the radio flare of Cyg X-3 in October 1985, when PeV radiation with no phase structure was seen. The PeV pulse was detected 3-5 days after the radio flare. The author proposes a natural explanation for the delay, in which gamma-photons of PeV energy are absorbed by radio radiation inside the source. After a delay, the gamma radiation emerges as the radio flux diminishes and absorption decreases. (author)