GLAST Testing of a Pulsar Model Matching H.E.S.S. Observations of LS 5039

• Published in: The Astrophysical journal Vol. 674; no. 2; pp. L89 - L92
• Main Authors: Sierpowska-Bartosik, Agnieszka, Torres, Diego F
• Format: Journal Article
• Language: English
• Published: Chicago, IL IOP Publishing 20.02.2008; University of Chicago Press
• Subjects: Astronomy; Earth, ocean, space; Exact sciences and technology; gamma rays: theory; Gamma radiation; Model matching; X-rays: binaries; X-ray binary stars; X-rays: individual (LS 5039); Pulsars; Binary X ray source; Cosmic x-ray sources; gamma rays: observations
• ISSN: 1538-4357; 0004-637X; 1538-4357
• DOI: 10.1086/529376

LS 5039 is one of a handful of X-ray binaries that have been recently detected at high-energy Y-rays, in this case, by the High Energy Stereoscopic System (H.E.S.S.). The nature of this system is unknown: both a black hole and a pulsar have been invoked as possible compact object companions. Here we work with a model of the high-energy phenomenology of the system in which it is assumed that the companion object is a pulsar rotating around an 06.5 V star in a similar to 3.9 day orbit. The model assumes two different sets of power-law spectral parameters of the interacting primary leptons corresponding to the two orbital phase intervals defined by H.E.S.S. as having different Y-ray spectra and very high energy (VHE) cutoffs. We show that the H.E.S.S. phenomenology is completely explained by this model. We present predictions for photons with lower energies (for E > 1 GeV), subject to test in the forthcoming months with the GLAST satellite. We find that GLAST will be able to judge on this model within 1 year.