Related papers: H-alpha Emission Variability in the gamma-ray Bina…
We present X-ray and optical observations of a new transient X-ray source in M31 first detected 23-May-2004 at R.A.=00:43:09.940 +/- 0.65'', Dec.=41:23:32.49 +/- 0.66''. The X-ray lightcurve shows two peaks separated by several months,…
A rare group of high mass X-ray binaries (HMXBs) are known that also exhibit MeV, GeV, and/or TeV emission ("gamma-ray binaries"). Expanding the sample of gamma-ray binaries and identifying unknown Fermi sources are currently of great…
Only a few binary systems with compact objects display TeV emission. The physical properties of the companion stars represent basic input to understand the physical mechanisms behind the particle acceleration, emission, and absorption…
We report on the optical spectroscopic monitoring of the X-ray transient MAXI J0709$-$159 (identified as the Be star LY CMa) performed for about 1.5 months after the X-ray detection with MAXI. The observed spectrum showed a double-peaked…
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…
Aims. The aim of this paper is to analyse the previously discovered discontinuity of the periodicity of the GeV $\gamma$-ray emission of the radio-loud X-ray binary LS I +61{\deg}303 and to determine its physical origin. Methods. We used…
Be/X-ray binaries are the most populous class of High Mass X-ray Binaries. Their X-ray duty cycle is tightly related to the optical companion wind activity, which in turn can be studied through optical spectroscopical dedicated…
We report on a 40ks Chandra observation of the TeV emitting high mass X-ray binary HESS J0632+057 performed in February 2011 during a high-state of X-ray and TeV activity. We have used the ACIS-S camera in Continuos Clocking mode to search…
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…
A mysterious X-ray-emitting object has been detected moving away from the high-mass gamma-ray binary PSR B1259-63, which contains a non-accreting pulsar and a Be star whose winds collide forming a complex interaction structure. Given the…
Gamma-ray binaries allow us to study physical processes such as particle acceleration up to very-high energies and gamma-ray emission and absorption with changing geometrical configurations on a periodic basis. They produce outflows of…
Observations of two well known binary systems (LS 5039 and LS I +61 303) with the satellite and Cherenkov telescopes revealed the broad band $\gamma$-ray spectra which seems to show two components, the first at GeV energies, showing…
We report on orbital modulation of the 100-600 MeV gamma-ray emission of the $P_{\rm B}=4.6$ hr millisecond pulsar binary PSR J2339$-$0533 using 11 yr of Fermi Large Area Telescope data. The modulation has high significance (chance…
Reliable determination of the basic physical properties of hot emission-line binaries with Roche-lobe filling secondaries is important for developing the theory of mass exchange in binaries. It is not easy, however, due to the presence of…
LS 5039 and LSI +61$\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…
Observations of the high-mass gamma-ray binary LS 2883/PSR B1259--63 with the Chandra X-ray Observatory during the 2011--2014 and 2014--2017 binary cycles have shown X-ray emitting clumps, presumably ejected from the binary during…
Using observations from Chandra, Swift and XMM-Newton, we investigate the high-energy properties of all known (18) Be+sdO systems as well as 7 additional Be binaries suspected to harbour stripped stars. The observed X-ray properties are…
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…
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…
The MAGIC collaboration has recently reported correlated X-ray and very high-energy gamma-ray emission from the gamma-ray binary LS I +61 303 during ~60% of one orbit. These observations suggest that the emission in these two bands has its…