Cherenkov Telescope results on gamma-ray binaries

TL;DR

Cherenkov telescopes have recently identified binary systems as a new class of Very High Energy gamma-ray sources, revealing diverse particle acceleration mechanisms and expanding the understanding of gamma-ray binaries.

Contribution

This paper reviews recent Cherenkov telescope observations of gamma-ray binaries, highlighting new detections and the phenomenology of key systems, and discusses ongoing searches for additional binaries.

Findings

Identification of three key VHE gamma-ray binaries: PSR B1259-63, LS 5039, LS I +61 303

Potential new members: HESS J0632+057 and Cyg X-1

Recent searches for other binaries like Cyg X-3 are ongoing

Abstract

In the past ten years of regular operations, a new generation of Cherenkov telescopes have established binary systems as a new class of Very High Energy gamma-ray (VHE) emitters. Particle acceleration in these systems may occur either in an accretion-powered jet (microquasar) or in the shock between a pulsar wind and a stellar wind (wind-wind). This paper describes the phenomenology of the three VHE binaries PSR~B1259-63, LS 5039 and LS I +61 303. Two other objects may belong to this new class: HESS J0632+057 is a point-like variable VHE source whose multiwavelength behaviour resembles that of the other binaries, whereas Cyg X-1 is a well-known accreting system which may have been detected in VHE during a flaring episode. The paper concludes with a review of the latest searches for other binaries with Cherenkov telescopes, with special emphasis on Cyg X-3.