Oscillation Induced Gamma Ray Emission from Dead Pulsars: A Model for Delayed GeV Emission in Gamma Ray Bursts
Session 53 -- Gamma Ray Bursts
Oral presentation, Thursday, June 15, 1995, 10:00am - 11:30am

## [53.05] Oscillation Induced Gamma Ray Emission from Dead Pulsars: A Model for Delayed GeV Emission in Gamma Ray Bursts

K. Y. Winnis Ding (Department of Physics and Astronomy, Rutgers University, Piscataway, NJ 08855-0849.), K. S. Cheng (Department of Physics, University of Hong Kong, Pokfulam, HK)

The oscillation of a crustal platelet of a neutron star will result in a high potential drop between the magnetic field lines. This potential drop can result in the emission of high energy curvature radiation photons with energy up to a few tens GeV. We consider the radiation processes that take place in the stellar magnetosphere and compute the energy spectrum escaping the magnetosphere.

The strain energy available decreases as the star radiates. Thus, the resultant potential drop decreases with time and results in a time delay in the emission of GeV photons. The delay time and the duration of the gamma ray emission process are consistent with the observed behaviour of the high energy gamma ray photons ($\sim 26$ GeV) in GRB~940217. These two time scales depend on the stored strain energy, the magnetic field and the period of the star. Our modelling spectrum also provides a good fit to the observed spectrum of the high energy GRB~930131.

The radiation processes result in the production of enormous amount of $e^{\pm}$. Line features are expected to be found in some of the gamma ray bursts in our model.

In conclusion, if some of the gamma ray bursts do come from the galactic neutron stars, our model provides a good explanation to the time scales and spectral features observed.