whole_DietersStefanStefanWilliamBoyd1990_thesis.pdf (17.64 MB)
Hard X-ray observations of Sco X-1 and GX 1+4
thesisposted on 2023-05-27, 00:01 authored by Dieters, Stefan W. B.(Stefan William Boyd)
Extra-solar X-ray astronomy started in 1962 with the detection of Sco X-1 and the galactic center during a rocket flight designed to find lunar X-rays. Since then, mainly as a result of a series of dedicated satellite missions the number of known (until 1984) X-ray sources had increased to about 1000. This number is comparable to the number stars brighter than 4th magnitude. The X-ray sky at this sensitivity appears as crowded as a moonlit night. The most comprehensive catalogue is that from the HEAO-1 satellite (1977/1978). This catalogue (Wood et al. 1984) lists 842 sources at energies below 20 keV. Unlike optical wavelengths about half the brightest soft to medium energy X-ray sources are associated with extra-galactic objects which are either galaxy groups or active galactic nuclei (AGN eg. Quasars, Seyfert, BL Lac). Fainter AGN may make up the bulk of the diffuse X-ray background. The galactic objects are mainly binary stars containing either a white dwarf or neutron star. The rest are stars with enhanced solar-like activity. The number of known X-ray sources is set to increase to about 100,000 ( much the same as number of stars visible with binoculars) with the completion of the present ROSAT survey. In a twist of history, one of the early ROSAT images actuality showed the moon.
Rights statementCopyright 1990 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s). Includes bibliographical references (p. 308-328)