Related papers: High-energy gamma-rays from Cyg X-1
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…
Bright sources of high energy electromagnetic radiation are widely employed in fundamental research as well as in industry and medicine. This steadily growing interest motivated the construction of several facilities aiming at the…
We report on Fermi/Large Area Telescope observations of the accreting black hole low-mass X-ray binary V404 Cygni during its outburst in June-July 2015. Detailed analyses reveal a possible excess of $\gamma$-ray emission on 26 June 2015,…
Using data from the All-Sky Monitor aboard the Rossi X-ray Timing Explorer (RXTE), we found that the 1.5-12 keV X-ray count rate of Cyg X-1 is, on time scales from 90 seconds to at least 10 days, strongly correlated with the spectral…
Very high energy (> 100 GeV) gamma-ray emission has been detected for the first time from the composite supernova remnant G0.9+0.1 using the H.E.S.S. instrument. The source is detected with a significance of 13 sigma, and a photon flux…
We report the detection of an unidentified gamma-ray source near the Galactic plane by the COMPTEL experiment aboard the Compton Gamma-Ray Observatory. The source is detected at a significance level of ~ 7.2 sigma in the energy range 1-3…
We study the contribution of thermal and non-thermal processes to the inverse Compton emission of the radio galaxy M 87 by modelling its broad-band emission. Through this we aim to derive insight into where within the AGN the X-ray,…
High-energy gamma-ray (>GeV) emission of gamma-ray bursts (GRBs) is very important in probing the jet evolution and particle acceleration of GRBs. The observations of high-energy photons are limited except for a few very bright GRBs,…
We investigate the contribution of the beamed jet component to the high energy emission in young and compact extragalactic radio sources, focusing for the first time on the gamma-ray band. We derive predictions on the gamma-ray luminosities…
High energy gamma-rays have been detected from Cygnus X-3, a system composed of a Wolf-Rayet star and a black hole or neutron star. The gamma-ray emission is linked to the radio emission from the jet launched in the system. The flux is…
In an effort to model the observed energy spectrum of Cygnus X-1 as well as its hard X-ray lag by Comptonization in inhomogeneous clouds of hot electrons with spherical geometry and various radial density profiles we discovered that: 1)…
We study theoretical interpretations of the 150-d (superorbital) modulation observed in X-ray and radio emission of Cyg X-1 in the framework of models connecting this phenomenon to precession. Precession changes the orientation of the…
We analyse five observations of the X-ray binary GX 339-4 by the soft gamma-ray OSSE detector on board CGRO simultaneous with either Ginga or RXTE observations. The source was bright during four of them, with the luminosity of L ~ 10^{37}…
Thanks to Hubble and Chandra telescopes, some of the large scale jets in extragalactic radio sources are now being observed at optical and X-ray frequencies. For the FR I objects the synchrotron nature of this emission is surely…
Using the RXTE/PCA data we study the fast variability of the reflected emission in the soft spectral state of Cyg X-1 by means of Fourier frequency resolved spectroscopy. We find that the rms amplitude of variations of the reflected…
We analyze all of the available {\it RXTE} observations of Cyg X-3 in order to investigate the connection between the central X-ray source and its surrounding environment. The hardness--intensity diagram of Cyg X-3 displays a "shoe" shape…
We report on our analysis of XMM-Newton observations of the Seyfert 2 galaxy ESO 138-G1 (z = 0.0091). These data reveal a complex spectrum in both its soft and hard portions. The 0.5-2 keV band is characterized by a strong 'soft-excess'…
The X-ray binary Cygnus X-3 is a highly variable X-ray source that displays a wide range of observed spectral states. One of the main states is significantly harder than the others, peaking at ~ 20 keV, with only a weak low-energy…
Cygnus X-1 is the archetypal black hole (BH) binary system in our Galaxy. We report the main results of an extensive search for transient gamma-ray emission from Cygnus X-1 carried out in the energy range 100 MeV - 3 GeV by the AGILE…
Prompt emission from the very fluent and nearby (z=0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of…