3 Hard gamma-ray afterglow

The 1.5 hours afterglow observed by EGRET in GRB of 17 February 1994 in the energy band (40-18000) MeV has a simple explanation in the local model. A nuclear explosion in the neutron star crust excites eigen-oscillations in the neutron star with periods (0.1-10) ms. In presence of such high frequency oscillations the old slowly rotating neutron star with a relatively small magnetic field becomes a transient high frequency radio pulsar. The radio pulsars are known as strongest sources in the hard gamma ray band of EGRET, so the observed hard gamma ray afterglow could be related to the activity of this transient high frequency radio pulsar (Bisnovatyi-Kogan 1995, 1997). To test this scheme it was suggested to perform high time resolution radio observations of the Vela pulsar shortly after the observed glitch, which happen almost every year. This proposal (Bisnovatyi-Kogan & Tsarevsky 1998) is now under consideration.