Related papers: Characterizing the VHE emission of LS I +61 303 us…
The gamma-ray binary LS I+61 303 has been widely monitored at different wavelengths since its discovery more than sixty years ago. However, the nature of the compact object and the peculiar behavior of the system are still largely debated.…
Accretion models predict two ejections along the eccentric orbit of LS I +61 303: one major ejection at periastron and a second, lower ejection towards apastron. We develop a physical model for LS I +61 303 in which relativistic electrons…
The gamma-ray binary HESS J0632+057 has been observed at very-high energies for almost ten years by all major systems of imaging atmospheric Cherenkov telescopes. We present new observations taken by the VERITAS observatory and an updated…
Gamma-ray binary LS I+61$^{\circ}$ 303 consists of a neutron star orbiting around a Be star with a period of $P_{\rm orb}\simeq26.5\ {\rm d}$. Apart from orbital modulations, the binary shows long-term flux variations with a superorbital…
PSR B1259-63/LS 2883 is a binary system where a 48 ms pulsar orbits a massive Be star with a highly eccentric orbit (e=0.87) with a period of 3.4 years. The system exhibits variable, non-thermal radiation visible from radio to very high…
The binary system PSR B1259-63/LS 2883 consists of a 47.8 ms radio pulsar that orbits the companion Be star with a period of 3.4 years in a highly eccentric orbit. The system is well sampled in radio, X-rays, and TeV gamma-rays, and shows…
1ES 1218+304 is among a group of several TeV blazars that exhibit surprisingly hard energy spectra given their redshifts. The VERITAS collaboration has carried out an intensive observing campaign of 1ES 1218+304 in early 2009 to…
We report on X-ray and TeV gamma-ray observations of the pulsar/Be star binary PSR J2032+4127/MT91 213. PSR J2032+4127 is a 143-ms gamma-ray pulsar which shares a long period (45-50 year) and highly eccentric orbit with the massive Be star…
New generation TeV gamma-ray telescopes have discovered many new sources, including several enigmatic unidentified TeV objects. HESS J0632+057 is a particularly interesting unidentified TeV source since: it is a point source, it has a…
LS I +61 303 and LS 5039 are exceptionally rare examples of HMXBs with MeV-TeV emission, making them two of only five known or proposed "gamma-ray binaries". There has been disagreement within the literature over whether these systems are…
The gamma-ray binaries LS 5039 and LS I +61 303 have been detected by Cerenkov telescopes at TeV energies, exhibiting periodic behavior correlated with the orbital period. These gamma-ray binary systems have also been recently detected by…
LS I +61 303 is a puzzling object detected from radio up to high-energy gamma-rays. Variability has recently been observed in its high-energy emission. The object is a binary system, with a compact object and a Be star as primary. The…
Recent observations of the binary system LS5039 with the High Energy Stereoscopic System (H.E.S.S.) revealed that its Very High Energy (VHE) gamma-ray emission is modulated at the 3.9 days orbital period of the system. The bulk of the…
Context. LS I +61 303 is a member of the select group of gamma-ray binaries: galactic binary systems that contain a massive star and a compact object, show a changing milliarcsecond morphology and a similar broad spectral energy…
Blazars are the most abundant type of extragalactic gamma-ray source, usually presenting high variability across the electromagnetic spectrum. Their Very High Energy (VHE, above 0.1 TeV) emission has been studied in detail using Air…
Perhaps the most extreme examples of "Active OB stars" are the subset of high-mass X-ray binaries -- consisting of an OB star plus compact companion -- that have recently been observed by Fermi and ground-based Cerenkov telescopes like HESS…
Gamma-ray binaries are variable sources of GeV-to-TeV photons with the peak in their spectral energy distributions above 100 MeV. There are only five Galactic gamma-ray binaries known and the processes which govern particle acceleration,…
PSR B1259-63/LS 2883 is a binary system consisting of a 48 ms pulsar orbitting around a Be star with an orbital period of ~3.4 years. The system was detected at very high energies (VHE; E > 100 GeV) by the High Energy Stereoscopic System…
A few Galactic objects are known to be variable sources of photons with energies above 100 GeV. These systems are mostly binaries, where variability can often be connected to the orbital period. Particle acceleration and gamma-ray…
We report the results of XMM-Newton and BeppoSAX observations of the radio and X-ray emitting star LS I +61 303, likely associated with the gamma-ray source 2CG 135+01 and recently detected also at TeV energies. The data include a long…