Inverse Compton emission from relativistic jets in binary systems. Issue 2 (31st August 2018)

• Record Type: Journal Article
• Authors: Khangulyan, Dmitry; Bosch-Ramon, Valentí; Uchiyama, Yasunobu
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 481:Issue 2(2018)
• Page Start: 1455
• Page End: 1468
• Publication Date: 2018-08-31
• Subjects: radiation mechanisms: non-thermal -- methods: analytical -- binaries: general -- gamma-rays: stars; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty2356
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: The gamma-ray emission detected from several microquasars can be produced by relativistic electrons emitting through inverse Compton scattering. In particular, the GeV emission detected from Cygnus X-3, and its orbital phase dependence, strongly suggests that the emitting electrons are accelerated in a relativistic jet, and that the optical companion provides the dominant target. Here, we study the effects related to particle transport in the framework of the relativistic jet scenario. We find that even in the most compact binary systems, with parameters similar to Cygnus X-3, particle transport can have a substantial influence on the GeV light curve unless the jet is slow, β < 0.7. In more extended binary systems, strong impact of particle transport is nearly unavoidable. Thus, even for a very compact system such as Cygnus X-3, particle transport significantly affects the ability of one-zone models to infer the properties of the gamma-ray production site based on the shape of the GeV lightcurve. We conclude that a detailed study of the gamma-ray spectrum can further constrain the structure and other properties of the gamma-ray emitter in Cygnus X-3, although such a study should account for gamma–gamma attenuation, since it may strongly affect the spectrum above $5\rm \, GeV$ .