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Gamma-ray bursts (GRBs) are divided into short gamma-ray bursts (SGRBs) and long gamma-ray bursts (LGRBs) based on the bimodal distribution of their durations. LGRBs and SGRBs are typically characterized by different statistical…
The high-mass X-ray binary LS I +61{\deg}303 is composed of a Be-type star and a compact object. The emission is variable and periodic across the electromagnetic spectrum, from radio to very high-energy gamma rays. The orbital period is…
The knowledge of the physical conditions occurring in the relativistic jet of radio-loud active galactic nuclei (AGNs) is important to understand the mechanisms at the basis of their multiband emission. From parsec-scale radio observations…
Blazars present highly variable $\gamma$-ray emission. This variability, which can range from a few minutes to several years, is also observed at other wavelengths across the entire electromagnetic spectrum. We make use of the first 12…
Rotating axisymmetric objects amplify incoming waves by superradiant scattering. When enclosed in a cavity, the repeated interaction of a confined field with the object may trigger superradiant instabilities. Rotating binaries are…
There are only a few sources that are definitely known to be gamma-ray binaries. Two of these are listed as associations in the Fermi LAT Bright Source List. We are developing novel techniques to extract high signal-to-noise light curves of…
The binary system PSR B1259-63/LS 2883 is well sampled in radio, X-rays, and TeV gamma-rays, and shows orbital phase-dependent variability in these frequencies. The first detection of GeV gamma-rays from the system was made around the 2010…
Several binary systems have been detected at High Energy (HE, E > 100 MeV) and/or Very High Energy (VHE, E > 100 GeV) gamma rays. Some of them are X-ray binaries in which accretion feeds relativistic radio jets and powers the non-thermal…
Observations of the PSR B1259-63/SS2883 binary system using the CANGAROO-II Cherenkov telescope are reported. This nearby binary consists of a 48msec radio pulsar in a highly eccentric orbit around a Be star, and offers a unique laboratory…
A systematic search for cyclical sources of gamma-ray emission on the period range from days to years in the Fermi-LAT sky is performed. Looking for cyclical emission, the sky is binned into equal-area pixels and the generalised…
By virtue of their sub-hour orbital periods, ultra-compact X-ray binaries are promising sources for the space-borne gravitational-wave interferometers LISA, Taiji, and TianQin. Some of these systems contain a neutron star primary, whose…
Massive binaries are crucial laboratories that allow us to investigate processes occurring in quite extreme conditions, such as particle acceleration, high-energy emission, or even dust formation. All these processes are intimately…
Binary pulsar systems emit potentially detectable components of gamma ray emission due to Comptonization of the optical radiation of the companion star by relativistic electrons of the pulsar wind, both before and after termination of the…
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…
We used very long baseline interferometry to constrain the orbit of the binary system 2MASS J05082729-2101444. We observed the system with the VLBA in three epochs at a frequency of 4.85 GHz, which provides an angular resolution of about 3…
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…
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 discovery of emission of TeV gamma rays from X-ray binaries has triggered an intense effort to better understand the particle acceleration, absorption, and emission mechanisms in compact binary systems. Here we present the pioneering…
The observation and imaging of hundreds or thousands of radio sources with the technique of very long baseline interferometry (VLBI) is a computationally intensive task. However, these surveys allow us to conduct statistical investigations…
Consider binary system with a millisecond pulsar ejecting relativistic particles and an optical star emitting soft photons with the energy $\omega \simeq 1-10$ eV. These low-energy photons are scattered by the relativistic electrons and…