2017MNRAS.471.4228Y

The binary system HESS J0632+057 was recently detected by Fermi to possess orbital-modulated GeV emission. In this paper, we study the possibility that the compact companion of HESS J0632+057 is a pulsar. Under such a presumption, we focus on the high-energy emission mechanism of this system, which is as follows. The pulsar companion travels through the circumstellar disc of the main-sequence star twice in each orbit, when some of the matter is gravity captured. The captured matter develops an accretion disc around the pulsar, and from which the soft photons are inverse Compton scattered by the pulsar wind as the GeV emission from the system. With proper choice of parameters, SED and light curve that are in accordance with observations can be produced. We predict that the light curve of GeV emission has two peaks, the larger one is at around 0.4 after the periastron (or 0.1 after the X-ray maximum), while the smaller one is between phases 0 and 0.1, with integrated flux one-fourth of the larger one.