Monte-Carlo Simulations of Radio Emitting Secondaries in Gamma-Ray Binaries

Abstract

Several binary systems that contain a massive star have been detected in both the radio band and at very high energies. In the dense stellar photon field of these sources, gamma-ray absorption and pair creation are expected to occur, and the radiation from these pairs may contribute significantly to the observed radio emission. We aim at going deeper in the study of the properties, and in particular the morphology, of the pair radio emission in gamma-ray binaries. We apply a Monte-Carlo code that computes the creation location, the spatial trajectory and the energy evolution of the pairs produced in the binary system and its surroundings. The radio emission produced by these pairs, with its spectral, variability and spatial characteristics, is calculated as it would be seen from a certain direction. A generic case is studied first, and then the specific case of LS 5039 is also considered. We find that, confirming previous results, the secondary radio emission should appear as an extended radio structure of a few milliarcseconds size. This radiation would be relatively hard, with fluxes up to ~ 10 mJy. Modulation is expected depending on the gamma-ray production luminosity, system eccentricity, and wind ionization fraction, and to a lesser extent on the magnetic field structure. In gamma-ray binaries in general, the pairs created due to photon-photon interactions can contribute significantly to the core, and generate an extended structure. In the case of LS 5039, the secondary radio emission is likely to be a significant fraction of the detected core flux, with a marginal extension.

13 pages, 12 Figures, 2 Tables, to be published in PASJ (Publications of the Astronomical Society of Japan), in press

References in corpus (18)

• Gamma-ray binaries: pulsars in disguise ?
• Understanding the Very High-Energy Emission from Microquasars
• Modeling interaction of relativistic and nonrelativistic winds in binary system PSR 1259-63/SS2883. I.Hydrodynamical limit
• On the formation of TeV radiation in LS 5039
• Discovery of a point-like very-high-energy gamma-ray source in Monoceros
• HESS J0632+057 : A new gamma-ray binary?
• Periodic very high energy gamma-ray emission from LS I +61 303 observed with the MAGIC telescope
• Confirmation of persistent radio jets in the microquasar LS 5039
• The gamma-ray binary LS 5039: mass and orbit constraints from MOST observations
• Leptonic secondary emission in a hadronic microquasar model
• The magnetic field and the location of the TeV emitter in Cygnus X-1 and LS 5039
• The changing milliarcsecond radio morphology of the gamma-ray binary LS 5039
• Exploring the connection between the stellar wind and the non-thermal emission in LS 5039
• Pulsar wind zone processes in LS 5039
• Non-thermal emission from secondary pairs in close TeV binary systems
• Gamma-ray absorption in the microquasar SS433
• Studying the properties of the radio emitter in LS 5039
• Constraints on the Geometry of the VHE Emission in LS 5039 from Photon-Photon Deabsorption

Cited by in corpus (8)

• Periodic morphological changes in the radio structure of the gamma-ray binary LS 5039
• Direct Wind Accretion and Jet Launch in Binary Systems
• Binaries with the eyes of CTA
• On the origin of LS 5039 and PSR J1825-1446
• A dynamical and radiation semi-analytical model of pulsar-star colliding winds along the orbit: Application to LS 5039
• Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind
• Properties of a hypothetical cold pulsar wind in LS~5039
• Synergies in extragalactic and Galactic jet research