GAMMA-RAY OBSERVATIONS OF PULSARS

We report on Compton Gamma Ray Observatory observations of six detected pulsars: the Crab, Vela, Geminga, PSR B1509-58, PSR B1706-44, and PSR B1055-52. We combine these data with radio data and X-ray data to provide an overview of what is known about gamma-ray pulsars. We discuss light curves, spectra, and radio/gamma-ray phase offsets, and present several tentative patterns in the data. These include constant phase with gamma-ray energy; a correlation between gamma-ray and X-ray luminosity; an anticorrelation between the gamma-ray luminosity and the efficiency in converting rotational energy loss into gamma-ray flux; and a correlation between the pulsar period and radio/gamma-ray phase offset. We also suggest that the emission models that have been proposed to date cannot explain the similarities of the average gamma-ray light curves observed over a wide range of energies. Further, unless a narrow beam is assumed, pulsars such as PSR B1055-52 and Geminga appear to be radiating a significant fraction of their rotational energy loss in the form of gamma rays.