Gamma-ray burst and the collapse of a white dwarf.

The temporal behavior of the gamma-ray burst GB790305 is interpreted in the context of a nonexplosive collapse of a white dwarf exceeding its mass limit. The energy of the impulsive phase of GB 790305 is due to the initial rapid cooling of the surface of the newly formed neutron star. The light curve of this phase has the shape of a diffusion curve due to the presence of a cold atmosphere. The exponential decay of the burst is the cooling phase of the neutron star, where surface radiation losses are balanced by thermal conduction heat transport. A two-dimensional approximation of the cooling problem gives a cooling curve which is a good fit to the observed luminosity curve. The scattering optical depth required for the diffusion curve is consistent with the apparent deformation due to Compton losses of the spectrum of the impulsive phase. The nature of three follow-up bursts is discussed in the context of neutron star glitches.