The Magnetospheric Flare on Compact Magnetized Object (Neutron Star or   White Dwarf) - Model for Cosmological Gamma-Ray Burst (GRB)
  The SN explosion in the closed binary can give the magnetospheric flare possessing the properties of GRB. The SN shock, flowing around the magnetosphere of a magnetized neutron star or a white dwarf, produces a narrow magnetic tail 10^9 cm long, 10^8 cm wide and a magnetic field of 10^6 Gauss. Fast particles (Lorentz factor of 10^4), generated in the tail by reconnection processes, radaite gamma rays of the 100 KeV - 1 MeV energies. The duration of radiation T<1 sec corresponds to a short GRB. Apart, the powerful shock can tear and accelerate part of the tail. That is the relativistic, strongly magnetized jet, producing gamma radiation and also X-rays and optic afterglow. That is long (T> 10 sec) GRB. The duration of the afterglow is inversly proportional to the photon energy and is several months for optic. 
Ya.N. Istomin, B.V. Komberg