Illustration of the binary geometry. The interaction between the pulsar wind and stellar outflows forms a terminal shock with a bow-shape geometry. The electrons from the pulsar wind are accelerated to very high energies by the shock, and then emit the keV X-rays and TeV γ-rays through synchrotron radiation and IC scattering, respectively. The shadow area is the stellar disc of the Be star projected on the orbital plane. The direction towards the Earth is indicated in the plot.