Related papers: One-dimensional pair cascade emission in gamma-ray…
Aims: LS 5039 is an enigmatic high-mass gamma-ray binary which hosts a powerful O6.5V companion, but the nature of the compact object is still to be established using multi-wavelength observations. Methods: We analyzed phase-resolved…
The propagation of high energy (HE, $E_\gamma>100$ MeV) and very high-energy gamma-rays (VHE, $E_\gamma>100$ GeV) in the extra-galactic photon field leads to pair-production and consequently energy- and distance-dependent attenuation of the…
We consider the propagation of very high energy (VHE) gamma-rays in the radiation field of the massive star of binary system Cen X-3. VHE gamma-rays or electrons, injected by the compact object close to the surface of a massive companion,…
PSR B1259-63/LS 2883 is a very high energy (VHE; $E > 100$ GeV) {\gamma}-ray emitting binary consisting of a 48 ms pulsar orbiting around a Be star with a period of $\sim3.4$ years. The Be star features a circumstellar disk which is…
Context. Very high-energy (VHE) $\gamma$-ray measurements of distant TeV blazars can be nicely explained by TeV spectra induced by ultra high-energy cosmic rays. Aims. We develop a model for a plausible origin of hard spectra in distant TeV…
The blazar 3C 279 emits a flux of gamma-rays that is variable on timescales as short as the light-crossing time across the event horizon of its central black hole. It is commonly reported that the spectral energy distribution (SED) does not…
We report the Fermi Large Area Telescope (Fermi-LAT) detection of the gamma-ray emission towards the young massive star cluster RSGC 1. Using the latest source catalog and diffuse background models, we found that the diffuse gamma-ray…
Beams of ultra-relativistic electrons in blazar jets develop pair cascades interacting with ambient soft photons. Employing coupled kinetic equations with escape terms, we model the unsaturated pair cascade spectrum. We assume that the…
Gamma-ray binaries are systems that emit non-thermal radiation peaking at energies above 1 MeV. One proposed scenario to explain their emission consists of a pulsar orbiting a massive star, with particle acceleration taking place in shocks…
A population of Galactic gamma-ray binaries is currently emerging due to ever increasing sensitivity of gamma-ray observatories. The detection of very high energy (VHE) photons with energies well above 10 TeV from a dozen of sources and the…
The growing number of extragalactic high-energy (HE, E > 100 MeV) and very-high-energy (VHE, E > 100 GeV) gamma-ray sources that do not belong to the blazar class suggests that VHE gamma-ray production may be a common property of most…
During last years a few massive binary systems have been detected in the TeV gamma-rays. This gamma-ray emission is clearly modulated with the orbital periods of these binaries suggesting its origin inside the binary system. In this paper…
We present a search for magnetically broadened gamma-ray emission around active galactic nuclei (AGN), using VERITAS observations of seven hard-spectrum blazars. A cascade process occurs when multi-TeV gamma rays from AGN interact with…
LS 5039 is among the most interesting VHE sources in the Galaxy. Two scenarios have been put forward to explain the observed TeV radiation: jets vs pulsar winds. The source has been detected during the superior conjunction of the compact…
LS 5039 and LSI +61$\degr$303 are two binaries that have been detected in the TeV energy domain. These binaries are composed of a massive star and a compact object, possibly a young pulsar. The gamma-ray emission would be due to particle…
Recent HESS observations show that microquasars in high-mass systems are sources of VHE gamma-rays. A leptonic jet model for microquasar gamma-ray emission is developed. Using the head-on approximation for the Compton cross section and…
Accretion onto neutron stars (NSs) in X-ray pulsars (XRPs) results in intense X-ray emission, and under specific conditions, high-energy nuclear interactions that produce gamma-ray photons at discrete energies. These interactions are…
Recent theoretical predictions of the lowest very high energy (VHE) luminosity of SN 1006 are only a factor 5 below the previously published H.E.S.S. upper limit, thus motivating further in-depth observations of this source. Deep…
Massive hot stars produce dense ultraviolet (UV) photon fields in their surroundings. If a very high-energy (VHE) gamma-ray emitter is located close to the star, then gamma-rays are absorbed in the stellar photon field, creating secondary…
Gamma-ray binaries are orbital modulated gamma-ray sources in the Galaxy detected both at GeV and TeV energies. The high-energy radiation may come from the interaction of energetic electrons injected by a young pulsar and photons from the…