Related papers: Wind accretion in Cygnus X-1
Long time scale radio-X-ray correlations in black holes during the hard state have been found in many sources and there seems to emerge a universal underlying relationship which quantitatively describes this behavior. Although it would…
The hard X-rays in Cyg X-1 and similar black hole sources are possibly produced in an active corona atop an accretion disk. We suggest that the observed weakness of X-ray reflection from the disk is due to bulk motion of the emitting hot…
We present a large-scale study of diffuse X-ray emission in the nearby massive stellar association Cygnus OB2 as part of the Chandra Cygnus OB2 Legacy Program. We used 40 Chandra X-ray ACIS-I observations covering $\sim$1.0 deg$^2$. After…
Jets powered by high-mass X-ray binaries must traverse the powerful wind of the companion star. We present the first global 3D simulations of jet-wind interaction in high-mass X-ray binaries. We show that the wind momentum flux intercepted…
We have analyzed approximately 1100 days of Cygnus X-1 hard X-ray data obtained with BATSE to study its rapid variability. We find for the first time correlations between the slope of the spectrum and the hard X-ray intensity, and between…
We have used observations of Cygnus X-1 from the Compton Gamma-Ray Observatory (CGRO) and BeppoSAX to study the variation in the MeV gamma-ray emission between the hard and soft spectral states, using spectra that cover the energy range 20…
The bright and highly variable X-ray and radio source known as Cygnus X-3 was among the first X-ray sources discovered, yet it remains in many ways an enigma. Its known to consist of a massive, Wolf-Rayet primary in an extremely tight orbit…
X-ray emission associated to accretion onto compact objects displays important levels of photometric and spectroscopic time-variability. When the accretor orbits a Supergiant star, it captures a fraction of the supersonic radiatively-driven…
In wind-fed X-ray binaries, the radiatively driven wind of the primary star can be suppressed by the EUV irradiation of the compact secondary star, leading to an increased accretion rate. This causes feedback between the released accretion…
Vela X-1 is among the best studied and most luminous accreting X-ray pulsars. The supergiant optical companion produces a strong radiatively-driven stellar wind, which is accreted onto the neutron star producing highly variable X-ray…
We present observations of a transient He-like Fe K alpha absorption line in Suzaku observations of the black hole binary Cygnus X-1 on 2011 October 5 near superior conjunction during the high/soft state, which enable us to map the full…
We present in this paper a first step toward a semi-analytical treatment of the accretion process in wind-fed neutron star supergiant X-ray binaries with eccentric orbits. We consider the case of a spherically symmetric wind for the…
Below an accretion rate of approximately a few per cent of the Eddington accretion rate, X-ray binary systems are not usually found in the soft spectral state. However, at accretion rates a factor of a few lower still, in the hard state,…
In recent years, accurate observational constraints become available for an increasing number of Galactic X-ray binaries. Together with proper motion measurements, we could reconstruct the full evolutionary history of X-ray binaries back to…
Black holes are the simplest possible objects, characterised by only mass and spin. We see them via accretion, so there is one more fundamental parameter which is the mass accretion rate. Here I will review how the data from both stellar…
We address the problem where the X-ray emission lines are formed and investigate orbital dynamics using Chandra HETG observations, photoionizing calculations and numerical wind-particle simulations.The observed Si XIV (6.185 A) and S XVI…
There have been a number of recent spectral models that have been successful in reproducing the observed X-ray spectra of galactic black hole candidates (GBHC). However, there still exists controversy over such issues as: what are the…
The clumping of massive star winds is an established paradigm, which is confirmed by multiple lines of evidence and is supported by stellar wind theory. We use the results from time-dependent hydrodynamical models of the instability in the…
We observed the Galactic black hole Cygnus X-1 with the Chandra High Energy Transmission Grating Spectrometer for 30 kiloseconds on 4 January, 2001. The source was in an intermediate state, with a flux that was approximately twice that…
The microquasar Cygnus X-1 displays the two typical soft and hard X-ray states of a black-hole transient. During the latter, Cygnus X-1 shows a one-sided relativistic radio-jet. Recent detection of the system in the high energy (HE;…