LIMITS ON THE GALACTIC MODEL OF GAMMA-RAY BURSTS

The Burst and Transient Source Experiment (BATSE) has shown that the s ky distribution of gamma-ray bursts (GRBs) is remarkably isotropic but non-uniform, which implies that the observed bursts may occur either in an extended galactic halo or at cosmological distances. For the Gal actic origin, Hartmann & Narayan have argued that the rotational energ y of neutron stars is insufficient by orders of magnitude to provide t he observed burst rate. Here we have calculated the period distributio n of dead pulsars and found that the rotational energy of neutron star s may indeed be insufficient to account for the total observed energy of the bursts, because only a small fraction (similar to I-p/I) of rot ational energy can be converted into gamma-rays if GRBs are produced b y glitches. Furthermore, it is difficult to establish high-velocity ne utron stars as a subclass of observed gamma-ray bursts since the obser ved burst rate is small, similar to 10 yr(-1).