Review of binary systems seen in gamma rays
I will review the current state of the art in available data and emission models of binary systems at high- (0.1-100GeV) and very-high-energy (>100GeV) gamma rays. The majority among these systems consists of an early type star with a strong stellar wind and a compact companion. Commonly accepted models assume that the compact object is a pulsar having a pulsar wind driven by the pulsar's spin-down power. An alternative scenario is Microquasar model, where a collimated relativistic jet associated with the compact object is observed and suspected to be connected to the detected high-energy emission. A closer look to the known binary systems reveals distinctive aspects regarding orbital parameters and/ or the nature of binary constituents. I will discuss the long-sought question whether or not gamma-ray binaries can be understood in terms of variations from an underlying, generalized scheme reviewing the sources known up to now. Furthermore, I will give an outlook what future instruments can do to advance the field.