A model of short gamma-ray bursts: Heated neutron stars in close binary systems

In this paper we present a model for the short (<1 s) population of gamma-ray bursts. In this model heated neutron stars in a close binary system near its last stable orbit emit a large amount of neutrinos (similar to 10(53) ergs). A fraction of these neutrinos will annihilate to form an e(+)e(-) pair plasma wind that will, in turn, expand and recombine to photons that make the gamma-ray burst. We study neutrino annihilation and show that a substantial fraction (similar to 1/2) of the energy deposited into e(+)e(-) pairs comes from interstar neutrinos, where each member of the neutrino pair originates from each neutron star. Thus, in addition to the annihilation of neutrinos blowing off of a single star, there is a new source of baryon-free plasma that is deposited between the stars. To model the e(+)e(-) pair plasma wind between stars, we do three-dimensional relativistic numerical hydrodynamic calculations. We find that the timescale for these bursts, deriving from the baryon-free plasma, is less than 1 s and that they will have a hot spectrum similar to 5 MeV. The energy in bursts is of the order of 10(52) ergs.