Gamma-ray bursts from high-velocity neutron stars

We investigate the viability of Galactic corona models of gamma-ray bursts by calculating the spatial distribution expected for a population of high-v elocity neutron stars born in the Galactic disk and moving in a gravitation al potential that includes contributions from the bulge, disk, and dark mat ter halo of our Galaxy and also from these same components of our neighbori ng galaxy M31. We consider two classes of models: one in which the bursts r adiate isotropically and one in which the bursts are beamed. We place const raints on these models by comparing the expected brightness and angular dis tributions with the data in the BATSE 3B catalog. We find that if the burst s radiate isotropically, then the Galactic corona model can reproduce the B ATSE peak Bur and angular distributions for neutron star kick velocities v( kick) greater than or similar to 800 km s(-1), source turn-on ages t(on) gr eater than or similar to 20 Myr, and BATSE sampling distances 130 kpc less than or similar to d(max) less than or similar to 350 kpc. If the bursts ar e instead beamed with an opening half-angle theta(b), no turn-on age is req uired, and the model can reproduce the BATSE data for 15 degrees less than or similar to theta(b) less than or similar to 20 degrees and 80 kpc less t han or similar to d(max) less than or similar to 250 kpc.