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|Title:||X-ray observations of SS 433 and the QSO MR 2251 - 178.|
|Presented at:||University of Leicester|
|Abstract:||This thesis reports the results of the X-ray observations of the galactic binary source SS 433 and the QSO MR 2251 - 178 made with the EXOSAT and GINGA X-ray satellites. The EXOSAT and GINGA study of SS 433 shows that both the X-ray intensity and spectrum of the binary vary over the periods of the 163 day jet precession and the 13 day binary motion. The X-ray luminosity of SS 433 is high at the phase corresponding to the maximum separation of the Doppler-shifted optical lines, and low when the jets become edge-on. An intensity decrease of up to 50% can be seen in each energy channel while the source changes from high to low luminosity. Over the 13 day binary cycle, the X-ray source is eclipsed by the companion star at the phase of the primary optical minimum. Five such events were observed by the EXOSAT and GINGA satellites at different phases of jet precession. The X-ray spectrum of SS 433 consists of a thermal continuum and a Doppler energy shifted broad emission line. It is proved, in this thesis, that the X-ray emission of SS 433 originates in the jets and is thermal in nature. The X-ray sources of SS 433 are stable and its properties are strongly modulated by the relativistic motion of the X-ray emitting material in the jets, the jet precession and the binary motion. With the constraints from the X-ray observations, a general picture of the X-ray jets of SS 433 is established in this thesis. The X-ray jets are a continuous super-sonic plasma flow and are generated inside the funnels of a thick accretion disc located around a black hole. Variable X-ray absorption and soft X-ray excess are found in the X-ray spectrum of MR 2251 - 178 with the EXOSAT observations. While there is an overall correlation between the ME(2-10 keV) and LE(0.1-2 keV) fluxes the pattern of variability can not be described by simple intensity, absorption or slope variations. It is shown, in this thesis, that it is possible to explain all the observed features by adopting the 'warm' absorber model in which the absorbing material is partially ionized by the flux of extreme ultra-violet and X-ray photons from the central continuum source. The preferred location of the absorbing material is close to the central continuum source. The recent evidence for 'cool' material in the centre of Seyfert galaxies is thus extended to include an object of significantly higher luminosity.|
|Rights:||Copyright © the author. All rights reserved.|
|Appears in Collections:||Theses, Dept. of Physics and Astronomy|
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