Related papers: Time variability of the $\gamma$-ray binary HESS J…
Gamma-ray emitting binaries (GREBs) are complex systems. Its study became in the last years a major endeavour for the high-energy astrophysics community, both from an observational and a theoretical perspective. Whereas the accumulation of…
LS 5039/RX J1826.2-1450 is one of the few High Mass X-ray binary systems from which radio and high energy TeV emission has been observed. Moreover, variability of the TeV emission with orbital period was detected. We investigate the hard…
Very high energy (VHE; energy $E \gtrsim 100\,$GeV) $\gamma$-rays originating from extragalactic sources undergo pair production with low-energy photons of background radiation fields. These pairs can inverse-Compton-scatter background…
We observed the unidentified TeV gamma-ray source HESS J1804-216 with the CANGAROO-III atmospheric Cerenkov telescopes from May to July in 2006. We detected very high energy gamma rays above 600 GeV at the 10 sigma level in an effective…
LS I +61$^\circ$ ~303 is one of around ten gamma-ray binaries detected so far which has a spectral energy distribution dominated by MeV-GeV photons. It is located at a distance of 2 kpc and consists of a compact object (black hole or…
The H.E.S.S. Imaging Atmospheric Cherenkov Telescope Array is currently the most sensitive instrument for Very High Energy (VHE) gamma-ray observations in the energy range of about 0.1-10 TeV. During more than two years of operation with…
Optical and near-infrared observations are compiled for the three gamma-ray binaries hosting Be stars: PSR B1259-63, LSI+61 303, and HESS J0632+057. The emissions from the Be disk are considered to vary according to the changes in its…
Gamma-ray binaries are stellar systems containing a neutron star or black hole with gamma-ray emission produced by an interaction between the components. These systems are rare, even though binary evolution models predict dozens in our…
Context: The detection of gamma-rays in the very-high-energy (VHE) range (100 GeV-100 TeV) offers the possibility of studying the parent population of ultrarelativistic particles found in astrophysical sources, so it is useful for…
We studied the rapid variability at GeV gamma rays of the flat-spectrum radio quasar PKS 1222+216, which was recently found by the MAGIC Cerenkov telescope to display very short variability (minutes time scale) at hundreds of GeV. We…
In this paper we report on the analysis of all the available optical and very high-energy $\gamma$-ray ($>$200 GeV) data for the BL Lac object PKS 2155$-$304, collected simultaneously with the ATOM and H.E.S.S. telescopes from 2007 until…
Recently, the $\gamma$-ray emission at MeV and GeV energies from the object LMC P3 in the Large Magellanic Cloud has been discovered to be modulated with a 10.3-days period, making it the first extra-galactic $\gamma$-ray binary. This work…
We present an analysis of long-term optical monitoring observations and optical spectroscopic observations of the counterpart to CXOU J205847.5+414637 (high mass X-ray binary system). We search for a variability in the light curve of Be…
The high-frequency peaked BL Lac object 1ES 0229+200 (z = 0.14) was first detected in very high energy (VHE, E > 100 GeV) $\gamma$-rays by the H.E.S.S. (High Energy Stereoscopic System) collaboration in 2006. No flux variability was…
We report the discovery of variable $\gamma$-rays up to petaelectronvolt from Cygnus X-3, an iconic X-ray binary. The $\gamma$-ray signal was detected with a statistical significance of approximately 10 $\sigma$ by the Large High Altitude…
Compact binary systems can provide us with unique information on astrophysical particle acceleration and cosmic ray production. However, only five binary systems have ever been observed in TeV $\gamma$ rays. The High Altitude Water…
HESS J0632+057 is an eccentric gamma-ray Be binary that produces non-thermal radio, X-rays, GeV, and very high-energy gamma rays. The non-thermal emission of HESS J0632+057 is modulated with the orbital period, with a dominant maximum…
While the data analysis of $\gamma$-ray telescopes has now become more robust, some signals may be misinterpretations of a time-variable foreground emission from the Solar System, induced by low-energy cosmic-ray interactions with…
The source J 1128+5925 was found recently to show strong intraday variability at radio wavelengths and its radio variability may come from interstellar scintillation. In optical, the object was quiet in our 2007 monitoring session. Here we…
Recent observations of binary systems obtained with the H.E.S.S. telescopes are providing crucial information on the physics of relativistic outflows and the engines powering them. We report here on new H.E.S.S. results on HESS J0632+057,…