Related papers: Gamma-rays from the binary system containing PSR J…
We investigated the multiband emission from the pulsar binaries XSS J12270-4859, PSR J2039-5617, and PSR J2339-0533, which exhibit orbital modulation in the X-ray and gamma-ray bands. We constructed the sources' broadband spectral energy…
2HWC J1928+177 is a Galactic TeV gamma-ray source detected by the High Altitude Water Cherenkov (HAWC) Observatory up to ~ 56 TeV. The HAWC source, later confirmed by H.E.S.S., still remains unidentified as a dark accelerator since there is…
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…
Combined X-ray synchrotron and inverse-Compton gamma-ray observations of pulsar wind nebulae (PWN) may help to elucidate the processes of acceleration and energy loss in these systems. In particular, such observations provide constraints on…
PSR B1259-63/LS2883 is a binary system composed of a pulsar and a Be star. The Be star has an equatorial circumstellar disk (CD). The {\it Fermi} satellite discovered unexpected gamma-ray flares around 30 days after the last two periastron…
The TeV gamma-ray point source HESSJ1832-093 remains unidentified despite extensive multi-wavelength studies. The gamma-ray emission could originate in a very compact pulsar wind nebula or an X-ray binary system composed of the X-ray source…
We study mechanisms of multi-wavelength emissions (X-ray, GeV and TeV gamma-rays) from the gamma-ray binary LS~5039. This paper is composed of two parts. In the first part, we report on results of observational analysis using four year data…
Diffusive TeV gamma-ray emissions have been recently discovered extending beyond the pulsar wind nebulae of a few middle-aged pulsars, implying that energetic electron/positron pairs are escaping from the pulsar wind nebulae and radiating…
We report the detection of GeV $\gamma$-ray emission from the very-high-energy (VHE) $\gamma$-ray source VER J2227+608 associated with the "tail" region of SNR G106.3+2.7. The GeV $\gamma$-ray emission is extended and spatially coincident…
The high-energy radiation from short period binaries containing a massive star with a compact relativistic companion was detected from radio to TeV gamma rays. We show here that PeV regime protons can be efficiently accelerated in the…
Gamma-ray binaries are thought to be composed of a young pulsar in orbit around a massive O or Be star, with their gamma-ray emission powered by pulsar spindown. The number of such systems in our Galaxy is not known. We aim to estimate the…
Gamma-ray binaries are systems composed of a compact object orbiting a massive companion star. The interaction between these two objects can drive relativistic outflows, either jets or winds, in which particles can be accelerated to…
It is expected that high energy gamma-rays, if injected relatively close to the massive stars in binary systems LS 5039 and LSI 61 3003, should be strongly absorbed, initiating inverse Compton $e^\pm$ pair cascades in the anisotropic…
The binary system PSR B1259-63 consists of a 48 ms pulsar in a 3.4 year orbit around a Be star and unpulsed TeV gamma-ray emission has been detected near previous periastron passages. A likely source of the gamma-rays is the inverse Compton…
We observed the first unidentified TeV gamma-ray source TeV J2032+4130 with Suzaku. Owing to Suzaku's high sensitivity for detection of diffuse X-ray emission, we found two small structures in the TeV emitting region. One of them is…
The very high energy (VHE; >100 GeV) source HESS J0632+057 has been recently confirmed as a \gamma-ray binary, a subclass of the high mass X-ray binary (HMXB) population, through the detection of an orbital period of 321 days. We performed…
TeV gamma-ray emission has been recently observed from direction of a few open clusters containing massive stars. We consider the high energy processes occurring within massive binary systems and in their dense environment by assuming that…
Many of the recently discovered TeV gamma-ray sources are associated with pulsar wind nebulae (PWNe). In fact, they represent the most populous class of Galactic sources at TeV energies. In addition, HESS has also discovered, in a survey of…
HESS J1809$-$193 is one of the unidentified very-high-energy gamma-ray sources in the H.E.S.S. Galactic Plane Survey (HGPS). It is located in a rich environment, with an energetic pulsar and associated X-ray pulsar wind nebula, several…
Gamma-ray binaries are stellar systems for which the spectral energy distribution (discounting the thermal stellar emission) peaks at high energies. Detected from radio to TeV gamma rays, the gamma-ray binary LS I 61 303 is highly variable…