6 research outputs found
Spectroscopy of the Stellar Wind in the Cygnus X-1 System
The X-ray luminosity of black holes is produced through the accretion of material from their companion stars. Depending on the mass of the donor star, accretion of the material falling onto the black hole through the inner Lagrange point of the system or accretion by the strong stellar wind can occur. Cygnus X-1 is a high mass X-ray binary system, where the black hole is powered by accretion of the stellar wind of its supergiant companion star HDE226868. As the companion is close to filling its Roche lobe, the wind is not symmetric, but strongly focused towards the black hole. Chandra-HETGS observations allow for an investigation of this focused stellar wind, which is essential to understand the physics of the accretion flow. We compare observations at the distinct orbital phases of 0.0, 0.2, 0.5 and 0.75. These correspond to different lines of sight towards the source, allowing us to probe the structure and the dynamics of the wind
Variable doppler shifts of the thermal wind absorption lines in low-mass x-ray binaries
In this paper we address the general applicability of the method pioneered by
\citet{Zhang2012} in which the motion of the compact object can be tracked
using wind X-ray absorption lines. We present the velocity measurements of the
thermal wind lines observed in the X-ray spectrum of a few low-mass X-ray
binaries: GX 13+1, H 1743322, GRO J165540 and GRS 1915+105. We find that
the variability in the velocity of the wind lines in about all of the sources
is larger than conceivable radial velocity variations of the compact object. GX
13+1 provides a potential exception, although it would require the red giant
star to be massive with a mass of . We conclude that
the variability of the source luminosity occurring on a time scale of
days/months can affect the outflow properties making it difficult to track the
orbital motion of the compact object using current observations. Given the
intrinsic variability of the outflows we suggest that low-mass X-ray binaries
showing stable coronae instead of an outflow (e.g. 4U 125469, MXB 165929,
4U 162449) could be more suitable targets for tracking the orbital motion of
the compact object.Comment: 11 pages, 6 figures, accepted for publication in MNRAS; typos
corrected, references updated, clarification added in the introduction and
table 2, conclusions unchange
Preparing for the future Survey of Cleveland County Council staff opinion
Available from British Library Document Supply Centre- DSC:3278.6523(CCC-RIU-CR--903) / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo