Andrei F. Illarionov

Non-pulsed gamma radiation from a binary system with a pulsar

Consider binary system with a millisecond pulsar ejecting relativistic particles and an optical star emitting soft photons with the energy

Free-fall accretion and emitting caustics in wind-fed X-ray sources

\omega \simeq 1-10

Hard X-Ray-emitting Black Hole Fed by Accretion of Low Angular Momentum Matter

eV. These low-energy photons are scattered by the relativistic electrons and positrons of the pulsars wind. The scattered photons forms a wide spectrum from hard X-ray band up to gamma band

Non-pulsed Emission from the Binary System B1259-63

\epsilon \simeq 1-1000

The outflow regime of quasispherical accretion onto a compact X-ray object

GeV>.When the pulsar wind is isotropic the luminosity of gamma radiation

Small-scale inviscid accretion discs around black holes

L_\gamma =L_\gamma (\psi)

Angular momentum of a supermassive black hole in a dense star cluster

depends heavily on the angle

Compton Heating and Superthermal Electrons in Gamma-loud Active Galactic Nuclei

\psi

The outflowing regime of quasi-spherical accretion on to X-ray compact objects

between the directions to the optical star and to the observer from the pulsar. During the orbital motion this angle varies periodically giving rise to the periodical change of the observed intensity of the gamma radiation and its spectrum. We calculated the spectral shape of the scattered hard photons. Under the assumption that the energy losses of the relativistic particles are small we receive analytical formulas. We apply our results to the binary system PSR B1259-63 and show that if the wind from the Be star is accounted for then it is possible to reproduce the observed spectrum.

Self-Shielding of X-Rays and Gamma Rays in Compact Sources

In wind-fed X-ray binaries the accreting matter is Compton-cooled and falls freely on to the compact object. The matter has a modest angular momentum l and accretion is quasi-spherical at large distances from the compact object. Initially small non-radial velocities grow in the converging supersonic flow and become substantial in the vicinity of the accretor. The streamlines with l>(GMR∗)1/2 (where M and R∗ are the mass and radius of the compact object) intersect outside R∗ and form a two-dimensional caustic which emits X-rays. The streamlines with low angular momentum, l<(GMR∗)1/2, run into the accretor. If the accretor is a neutron star, a large X-ray luminosity results. We show that the distribution of accretion rate/luminosity over the star surface is sensitive to the angular momentum distribution of the accreting matter. The apparent luminosity depends on the side from which the star is observed and can change periodically with the orbital phase of the binary. The accretor then appears as a ‘Moon-like’ X-ray source.