Gamma ray binaries are composed of a massive star and a compact object (usually a neutron star or a black hole). Currently only a handful of binary systems are known to emit in the gamma ray domain. The origin of the emission is still debated: there are two competing scenarios, accreting versus non-accreting mechanisms. In the former, particle acceleration takes place via relativistic jet, while in the latter it occurs in schoks where the pulsar wind encounters the circumstellar environment and/or the wind from the companion star.

The data challenge involves different spectral shapes and different timescales of gamma intensity variability. This allows researchers to explore the observing time needed to unveil distinct and important spectral signatures and weak components.