In the second part of the dissertation I present the original work which I carried out for this project. This began as a purely instrumental project with the aim of developing high-resolution superconducting X-ray detectors. I have placed my work on kinetic inductance microcalorimeters in Appendix A. Although the project evolved into a mainly observational one, its unifying theme is the application of state of the art non-dispersive X-ray spectrometers to the study of Cen X-3.
Since I was working on the development of X-ray detectors which would
probably not be used in a mission for several years it seemed appropriate
to analyse some data from an existing state of the art X-ray telescope.
Dr Richard Kelley provided the data from the BBXRT observation of Cen X-3.
The analysis of these data is described in Chapter 5. The
X-ray spectroscopy results led us to propose for an observation of Cen X-3
with ASCA in order to further resolve the structure of the iron K
emission line and, in particular, to test my prediction that the 6.4 keV
line would be the one that pulsates. The proposal was accepted for ASCA's
AO-3 observational cycle and carried out in February 1995. The results are
in Chapter 7. The principal investigators were R. L. Kelley and
F. Nagase. I was a co-investigator. The other main result of the BBXRT
analysis was my prediction that there should be a cyclotron line in the
spectrum of Cen X-3 near 30 keV. In order to search for this, we proposed
to observe Cen X-3 with RXTE. I was the principal investigator. The
co-investigators were R. L. Kelley and K. Ebisawa. This observation was
carried out in September 1996 and the results are described
in Chapter 8. Meanwhile, Dr. Saequa Vrtilek provided me with
some EXOSAT GSPC observations of Cen X-3 in which I searched for a
cyclotron line. This analysis is presented in Chapter 6.
Finally, I summarize my results, discuss their relevance, and suggest some
future work in Chapter 9.
The research for this dissertation was carried out in the X-Ray Astrophysics branch of the Laboratory for High Energy Astrophysics at NASA's Goddard Space Flight Center and was supervised by Dr. Richard L. Kelley. Much of Chapter 5 has been published in the Astrophysical Journal (Audley et al. (1996)). Part of Appendix A has appeared in the Journal of Low Temperature Physics (Audley et al. (1993)). The contents of Chapters 6, 7, and 8 will be submitted for publication in the Astrophysical Journal in the near future.
To Anne-Marie.
I would like to thank Rich Kelley for all of the help and encouragement he has given me over the last few years. I am grateful to my academic advisor Elihu Boldt for his guidance. Without Gayle Rawley, who introduced me to cryogenic electronics and the help of John Gygax, Regis Brekosky, Scott Murphy, and Caroline Stahle the instrumental part of this project would not have been possible. I thank David Osterman for providing kinetic inductors for testing and for some fruitful discussions. I would like to thank Saequa Vrtilek for making her EXOSAT GSPC data available to me and for her many useful comments and suggestions. I would also like to thank Ken Ebisawa, Lorella Angelini, and Charles Day for answering my questions. I appreciate the suggestions of the dissertation committee. They helped make this dissertation better. I would also like to thank Randall Smith for reading the manuscript and Keith Gendreau for providing some of the figures.
This work was supported by NASA grant NAG5-1176. This research made use of data obtained through the High Energy Astrophysics Science Archive Research Center Online Service, provided by the NASA-Goddard Space Flight Center.