Dynamos, Super-pulsars and Gamma-ray bursts

The remnant of a neutron star binary coalescence is expected to be temporarily stabilised against gravitational collapse by its differential rotation. We explore the possibility of dynamo activity in this remnant and assess the potential for powering a short-duration gamma-ray burst (GRB). We analyse our three-dimensional hydrodynamic simulations of neutron star mergers with respect to the flow pattern inside the remnant. If the central, newly formed super-massive neutron star remains stable for a good fraction of a second an efficient low-Rossby number α −Ω-dynamo will amplify the initial seed magnetic fields exponentially. We expect that values close to equipartition field strength will be reached within several tens of milliseconds. Such a super-pulsar could power a GRB via a relativistic wind, with an associated spin-down time scale close to the typical duration of a short GRB. Similar mechanisms are expected to be operational in the surrounding torus formed from neutron star debris.