Related papers: Time variability of the $\gamma$-ray binary HESS J…
We report on observations of the pulsar / Be star binary system PSR J2032+4127 / MT91 213 in the energy range between 100 GeV and 20 TeV with the VERITAS and MAGIC imaging atmospheric Cherenkov telescope arrays. The binary orbit has a…
The mechanisms producing fast variability of the $\gamma$-ray emission in active galactic nuclei are under debate. The MAGIC telescopes detected a fast very high energy (VHE, E$>100$ GeV) $\gamma$-ray flare from BL Lacertae on 2015 June 15.…
Aims. We provide new insights into the nature of HESS J1857+026, a very-high-energy {\gamma}-ray source whose complex morphology in the TeV band was attributed to the superposition of two distinct sources. Methods. We performed radio…
For a long time XMMU J010331.7-730144 was proposed as a high-mass X-ray binary candidate based on its X-ray properties, however, its optical behaviour was unclear - in particular previous observations did not reveal key Balmer emission…
The high-energy gamma-ray emission discovered using the H.E.S.S. telescopes from the binary system PSR B1259 -63, is modelled using an extension of the approach that successfully predicted it. We find that the simultaneous INTEGRAL and…
The nature of the hard X-ray source XSSJ12270-4859 is still unclear though it was claimed to be a magnetic Cataclysmic Variable. We here present a broad-band X-ray and gamma ray study based on a recent XMM-Newton observation and archival…
The gamma-ray binary 1FGL J1018.6-5856 consists of an O6V((f)) type star and an unknown compact object, and shows orbitally modulated emission from radio to very high energy gamma rays. The X-ray light curve shows a maximum around the same…
The unidentified TeV gamma-ray source MGRO J1908+06/HESS J1908+063 was observed with the VERITAS Imaging Atmospheric Cherenkov Array during October 2007 and May-June 2008. This extended source is located on the galactic plane at a galactic…
Our understanding of the intensity distribution of the interstellar radiation background is based on the observational data from IRAS, COBE-FIRAS and Planck. The intensity of this radiation field increases rapidly towards the Galactic plane…
The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 hours,…
Context. The discovery of the unique source HESS J1507-622 in the very high energy (VHE) range (100 GeV-100 TeV) opened new possibilities to study the parent population of ultra-relativistic particles found in astrophysical sources and…
We discuss the optical light curves of two Be X-ray Binaries, IGR J06074+2205 and SAX J2103.5+4545 recovered from the ATLAS, ZTF and ASAS-SN databases. Both sources show long term optical variability of 620 and 420 days respectively, with…
The H.E.S.S. experiment, an array of four Imaging Atmospheric Cherenkov Telescopes with high sensitivity and large field-of-view, has been used to search for emitters of very-high-energy (VHE, >100 GeV) gamma-rays along the Galactic plane,…
High energy gamma-ray astronomy has recently made significant progresss through ground-based instruments like the {\it H.E.S.S.} array of imaging atmospheric Cherenkov telescopes. The unprecedented angular resolution and the large field of…
We have investigated the time variations in the light curves from a sample of long and short Fermi/GBM Gamma ray bursts (GRBs) using an impartial wavelet analysis. The results indicate that in the source frame, the variability time scales…
The results of GRANAT/SIGMA hard X-ray observations of GRS 1758-258 in 1990-1998 are presented. The source lies at ~5\arcdeg from the Galactic Center and was within the SIGMA field of view during the GRANAT surveys of this region. The total…
With the installation of a new 28-m diameter imaging atmospheric Cherenkov telescope in the middle of the array, the H.E.S.S. instrument has entered since 2012 into its Phase II. The fifth large-size telescope is particularly important to…
We report on a detailed analysis of the $\gamma$-ray light curve of NGC 1275 using the Fermi large area telescope data accumulated in 2008-2017. Major $\gamma$-ray flares were observed in October 2015 and December 2016/January 2017 when the…
We report the discovery of very-high-energy (VHE) gamma-ray emission of the binary system PSR B1259-63/SS 2883 of a radio pulsar orbiting a massive, luminous Be star in a highly eccentric orbit. The observations around the 2004 periastron…
LS I +61 303 is one of only a few high-mass X-ray binaries currently detected at high significance in very high energy gamma-rays. The system was observed over several orbital cycles (between September 2006 and February 2007) with the…