  Cygnus X-3 is an accreting high-mass X-ray binary composed of a Wolf-Rayet
star and an unknown compact object, possibly a black hole. The gamma-ray space
telescope Fermi found definitive evidence that high-energy emission is produced
in this system. We propose a scenario to explain the GeV gamma-ray emission in
Cygnus X-3. In this model, energetic electron-positron pairs are accelerated at
a specific location in the relativistic jet, possibly related to a
recollimation shock, and upscatter the stellar photons to high energies. The
comparison with Fermi observations shows that the jet should be inclined close
to the line of sight and pairs should not be located within the system.
Energetically speaking, a massive compact object is favored. We report also on
our investigations of the gamma-ray absorption of GeV photons with the
radiation emitted by a standard accretion disk in Cygnus X-3. This study shows
that the gamma-ray source should not lie too close to the compact object.
