Gamma radiation from rotation powered pulsars and results from the Energetic Gamma-Ray Experiment Telescope

The Polar Cap and Outer Gap models of gamma-ray emission from rotation-powered pulsars are examined. In the Polar Cap model, a detailed Monte Carlo calculation is performed: Electrons and positrons are accelerated in vacuum gaps near the magnetic polar cap of a rotating neutron star. The curvature radiation they emit interacts with the strong magnetic field of the pulsar and produces {dollar}esppm{dollar} pairs via the Sturrock process. These pairs in turn emit synchrotron radiation which also interacts with the strong magnetic field. An electromagnetic cascade results, and the gamma-ray flux seen at the Earth consists of the escaping curvature and synchrotron radiation. In the Outer Gap model, a much refined calculation of high energy emission from the outer gap region is performed. In this case, vacuum gaps form in the outer regions of the pulsar magnetosphere along the boundary between the "closed" and "open" field line zones. The large potential drops which are postulated to form in the outer gaps accelerate counter-streaming beams of electrons and positrons to highly relativistic energies {dollar}(Esb{lcub}e{rcub} sim 10sp{lcub}13{rcub}{dollar} eV). The curvature and inverse-Compton radiation emitted by these particle beams interact with lower energy radiation to produce secondary pairs of electrons and positrons. These secondary particles produce the synchrotron and inverse-Compton radiation which provides the required photon-photon opacity for the counter-streaming very high energy radiation. Improvements over previous outer gap calculations include a more detailed treatment of the high energy emission processes in the pulsar magnetosphere and the incorporation of particle and photon transport to and from different emitting regions. For both the Polar Cap and Outer Gap calculations, predictions of light curve shapes and spectral variation as a function of pulse phase are made using standard assumptions about the geometry of the pulsar magnetosphere.; A description of the EGRET instrument and the various data analysis methods is presented. Maximum likelihood techniques are used with calibration information including instrument efficiency, energy and angular resolution to determine fluxes, spectra and time variability for a variety of gamma-ray sources. Analyses of the high energy emission from the X-ray binary Cygnus X-3 and from the Crab Pulsar and Nebula are presented. A detailed study of the new source class of gamma-ray loud Active Galactic Nuclei (AGN) is performed in the context of the "unified picture". Source spectra, variability and source luminosity evolution are examined and related to the prevailing theoretical models.