Very high energy gamma-ray emission from X-ray transients during major outbursts

Abstract

Context: Some high mass X-ray binaries (HMXB) have been recently confirmed as gamma-ray sources by ground based Cherenkov telescopes. In this work, we discuss the gamma-ray emission from X-ray transient sources formed by a Be star and a highly magnetized neutron star. This kind of systems can produce variable hadronic gamma-ray emission through the mechanism proposed by Cheng and Ruderman, where a proton beam accelerated in the pulsar magnetosphere impacts the transient accretion disk. We choose as case of study the best known system of this class: A0535+26. Aims: We aim at making quantitative predictions about the very high-energy radiation generated in Be-X ray binary systems with strongly magnetized neutron stars. Methods: We study the gamma-ray emission generated during a major X-ray outburst of a HMXB adopting for the model the parameters of A0535+26. The emerging photon signal from the disk is determined by the grammage of the disk that modulates the optical depth. The electromagnetic cascades initiated by photons absorbed in the disk are explored, making use of the so-called "Approximation A" to solve the cascade equations. Very high energy photons induce Inverse Compton cascades in the photon field of the massive star. We implemented Monte Carlo simulations of these cascades, in order to estimate the characteristics of the resulting spectrum. Results: TeV emission should be detectable by Cherenkov telescopes during a major X-ray outburst of a binary formed by a Be star and a highly magnetized neutron star. The gamma-ray light curve is found to evolve in anti-correlation with the X-ray signal.

arXiv comment8 pages, 7 figures, accepted for publication in Astronomy and Astrophysical journal

References in corpus (18)

• Variable Very High Energy Gamma-ray Emission from the Microquasar LS I +61 303
• Discovery of the Binary Pulsar PSR B1259-63 in Very-High-Energy Gamma Rays around Periastron with H.E.S.S
• Discovery of very high energy gamma-rays associated with an X-ray binary
• Discovery of a High-Energy Gamma-Ray-Emitting Persistent Microquasar
• Constraining the population of cosmic ray protons in cooling flow clusters with gamma-ray and radio observations: Are radio mini-halos of hadronic origin?
• Hadronic gamma-ray emission from windy microquasars
• Gamma-ray absorption in massive X-ray binaries
• A broadband leptonic model for gamma-ray emitting microquasars
• Propagation of very high energy gamma-rays inside massive binaries LS 5039 and LSI +61 303
• Neutrinos from Accreting Neutron Stars
• Cyclical behaviour and disc truncation in the Be/X-ray binary A0535+26
• A 0535+26: Back in business
• Variable gamma-ray emission from the Be/X-ray transient A0535+26?
• Gamma-rays from cascades in close massive binaries containing energetic pulsars
• On the limit cycle instability in magnetized accretion discs
• Similarities and Differences between Relativistic Electron-Photon Cascades Developed in Matter, Photon Gas and Magnetic Field
• Ab initio simulations of accretion disks instability
• Gamma-Ray Emission From Be/X-Ray Binaries

Cited by in corpus (7)

• Dissecting the region of 3EG J1837-0423 and HESS J1841-055 with INTEGRAL
• Gamma-ray observations of the Be/pulsar binary 1A 0535+262 during a giant X-ray outburst
• Dynamical and radiative simulations of $\gamma$-ray jets in microquasars
• INTEGRAL and Swift observations of the Be X-ray binary 4U 1036-56 (RX J1037.5-5647) and its possible relation with gamma-ray transients
• Deep search for gamma-ray emission from the accreting X-ray pulsar 1A 0535+262
• Very-high-energy observations of the binaries V 404 Cyg and 4U 0115+634 during giant X-ray outbursts
• Probing the emission mechanism and nature of the pulsating compact object in the X-ray binary SAX J1324.4-6200