Neutron Star Binaries as Central Engines of GRBs

We describe the results high resolution, hydrodynamic calculations of neutron star mergers. The model makes use of a new, nuclear equation of state, accounts for multi-flavour neutrino emission and solves the equations of hydrodynamics using the smoothed particle hydrodynamics method with more than 106 particles. The merger leaves behind a strongly differentially rotating central object of ∼ 2.5 M⊙ together with a distribution of hot debris material. For the most realistic case of initial neutron star spins, no sign of a collapse to a black hole can be seen. We argue that the differential rotation stabilizes the central object for∼ 102 s and leads to superstrong magnetic fields. We find the neutrino emission from the hot debris around the freshly-formed, supermassive neutron star to be substantially lower than predicted previously. Therefore the annihilation of neutrino antineutrino pairs will have difficulties to power very energetic bursts (≫ 1049 erg).