Constraints on the Galactic Corona Models of Gamma-Ray Bursts From the 3B Catalogue

Abstract

We investigate the viability of Galactic corona models of gamma-ray bursts by calculating the spatial distribution expected for a population of high-velocity neutron stars born in the Galactic disk and moving in a gravitational potential that includes the Galactic bulge, disk, and a dark matter halo. We consider models in which the bursts radiate isotropically and in which the radiation is beamed. We place constraints on the models by comparing the resulting brightness and angular distributions with the data in the BATSE 3B catalog. We find that, if the burst sources radiate isotropically, the Galactic corona model can reproduce the BATSE peak flux and angular distributions for neutron star kick velocities > 800 km s$^{-1}$, source turn-on ages > 20 Myrs, and BATSE sampling distances 130 kpc < d_{max} < 350 kpc. If the radiation is beamed, no turn-on age is required and agreement with the BATSE data can be found provided that the width of the beam is less than 20 deg.