Very energetic gamma rays from binary x-ray sources and other astronomical objects

Abstract

This thesis describes the observation of a number of astronomical objects using the University of Durham Atmospheric Cerenkov light detectors. The array of telescopes was used to study the Very High Energy (V.H.E.) gamma-radiation from these objects from June 1981 until November 1984.The general features of Gamma-ray astronomy are briefly discussed, and a review of the main results of previous gamma-ray observations is given. The basic theory and general characteristics of Atmospheric Cerenkov Effect experiments are reviewed. Details of the design, operation and performance of the University of Durham facility are presented in addition to details of the improvements achieved in the development of a new telescope. In particular, the new optical system is described. The main analysis procedures are explained. The adaptation of statistical techniques used to analyse the intensity of the Cerenkov light flash is described in some detail. A discussion of the problems involved in conducting an extensive search for periodicity in the data collected from Cygnus X-3 is given. A procedure for testing for transient pulsed gamma-ray emission from the Crab Pulsar is also described. The results of the observations from several objects are presented., the binary X-ray sources, Cygnus X-3, Hercules X-l and 4U0115+63, the Crab pulsar and the Galactic Plane. In addition, the preliminary results from observations of seven radio pulsars and seven other objects are given. A review of the main production mechanisms of V.H.E. gamma-radiation is given with particular emphasis on the models proposed for the high energy processes in Cygnus X-3, other binary-ray sources and pulsars.