Mullard Space Science Laboratory

S. R. Rosen
X-ray and optical observations of the magnetic cataclysmic variables

1987 (supervisor: K. O. Mason)

This Thesis is in two main parts. The major portion concerns X-ray and optical observations of the AM Her and intermediate polar (IP) magnetic sub-classes of the cataclysmic variables (CVs), while a final chapter concerns the analyis of X-ray observations of the Fornax cluster of galaxies.

Chapter 1 presents a basic overview of the accretion process in CVs. A more detailed discussion of the accretion process in the magnetic systems is presented in the context of their observational properties.

Phase-resolved optical spectroscopy of the AM Her system E1405-451 is presented in chapter 2. A detailed radial velocity study of the multiple components in its emission lines leads to an estimate of the stellar masses and also, for the first time, allows a detailed picture of the accretion stream in this system to be constructed. The system geometry is revealed.

Extensive X-ray observations of the IP EX Hya are discussed in chapter 3. A comprehensive analysis of the X-ray energy dependence of both the modulation at the 67 minute white dwarf rotation period and the partial eclipse at the 98 minute binary orbital period indicates that the conventional occultation model for IPs is inadequate. A new, absorption model is advanced in chapter 4 in which the accretion shock height varies with azimuthal angle due to azimuth dependent accretion from a disk.

Chapter 5 present an analysis of the IP V1223 Sgr. The white dwarf rotation period is derived. It is found that a small fraction of the X-ray emission is modulated at the beat period in this system. Possible causes of the beat modulation are discussed. The data of other IPs are compared with the new model of chapter 4 and the occultation model.

Chapter 6 presents X-ray observations of the Fornax cluster of galaxies. Two galaxies are found to be strong X-ray emitters. This result is discussed in terms of cooling gas flows in each galaxy. However, their emission is superimposed on a much larger, diffuse X-ray emission whose origin is probably a hot tenuous intracluster medium.


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