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Possible explanation of the γ-ray light curve and time variability in Cygnus X-3

Abstract

Very high-energy (VHE) and ultra high-energy (UHE) γ rays, at around 1 TeV and 1 PeV respectively, have been observed from Cygnus X-3 predominantly in two distinct regions of orbital phase. Here we investigate whether this can be understood in terms of the accretion disk corona model of White and Holt1 developed to explain the asymmetric light curve of the low-mass X-ray binary system X1822–371. In this model, two bulges in the outer rim of the accretion disk are required to fit the observed X-ray light curve and we find these could provide target material for the production of the γ rays observed at two distinct phases. We show also that magnetic steering effects may be inevitable in Cyg X-3 and may lead to a natural explanation to the observed variability in flux and phase of γ-ray emission.

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Protheroe, R., Stanev, T. Possible explanation of the γ-ray light curve and time variability in Cygnus X-3. Nature 328, 136–139 (1987). https://doi.org/10.1038/328136a0

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