Abstract
The binary system Cygnus X-3 is a source of high energy γ rays (>1015 eV)1,2, and the existence of quiescent radio emission from this system3 is suggestive of a strong magnetic field extending well beyond the binary orbit4. We show here that the high-energy γ rays traversing this field could be attenuated by magnetic pair production process, resulting in the rather sharp steepening of the γ-ray spectrum beyond about 1016 eV. Using the observed spectral steepening2, we derive a magnetic field strength of 0.7 G in the region ∼1014 cm, where most of the observed radio emission takes place. The observed light curve above 1015 eV shows only one significant narrow peak at a phase of about 0.2 from the X-ray minimum. This could result from the magnetic bending of the charged particles from the pulsar before interacting with the enshrouded matter. We predict that the relative contribution of steady flux should increase beyond 1016 eV.
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Stephens, S., Verma, R. Magnetic pair production in Cygnus X-3 and a cut off in the γ-ray spectrum. Nature 308, 828–830 (1984). https://doi.org/10.1038/308828a0
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DOI: https://doi.org/10.1038/308828a0
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