GAMMA RAY PULSARS Multiwavelength Observations

High-energy gamma rays are a valuable tool for studying particle acceleration and radiation in the magnetospheres of energetic pulsars. The seven or more pulsars seen by instruments on the Compton Gamma Ray Observatory (CGRO) show that: the light curves usually have double-peak structures (suggesting a broad cone of emission); gamma rays are frequently the dominant component of the radiated power; and all the spectra show evidence of a high-energy turnover. For all the known gamma-ray pulsars, multiwavelength observations and theoretical models based on such observations offer the prospect of gaining a broad understanding of these rotating neutron stars. The Gamma-ray Large Area Space Telescope (GLAST), now in planning for a launch in 2007, will provide a major advance in sensitivity, energy range, and sky coverage. Introduction Pulsars are particularly interesting astrophysical objects because we know so much about them. Most of that information is derived from their timing properties. Measurement of the period P and period derivative Ṗ first identified pulsars as compact objects. Under fairly general assumptions that pulsars are rapidly-rotating neutron stars with a strong dipole magnetic field, a whole range of physical parameters can be estimated from these timing parameters. Examples include the timing age, the spin-down energy loss, the surface magnetic field, and the open field line voltage (Thompson, 2000).