Data Centre for Astrophysics
Astronomy Department of the University of Geneva
ISDC Seminar

Thursday, 24 January 2008 at 11:00

Andrzej Zdziarski
N. Copernicus Astronomical Center, Warsaw, Poland

The high-mass X-ray binaries Cyg X-3 and Cyg X-1

Abstract. I will discuss results of fitting the X-ray spectra of Cyg X-3 and the implications for the absorbing stellar wind. We measure the mass-loss rate and find it to agree with independent estimates. The wind is two-phase, with the filling factor of the clumpy part of ~0.01. The bolometric luminosity indicates the presence of a black-hole. Then I will discuss a study of precessional variability of Cyg X-1 and a discovery of an accretion bulge. Comptonization anisotropy of the X-ray emission of a precessing disc and Doppler anisotropy of the radio emission of a precessing jet explain well the superorbital periodicity of Cyg X-1. We find the disc tilt of ~10-20 degrees and the jet velocity of ~(0.3-0.5)c. Then we discover a dependence of the X-ray orbital modulation on the superorbital phase, which is well explained by absorption in a bulge at the disc outer edge.

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