Producing ultra-strong magnetic fields in neutron star mergers

Abstract

We report an extremely rapid mechanism for magnetic field amplification during the merger of a binary neutron star system. This has implications for the production of the short class of Gamma-Ray Bursts, which recent observations suggest may originate in such mergers. In detailed magnetohydrodynamic simulations of the merger process, the fields are amplified via Kelvin-Helmholtz instabilities beyond magnetar field strength and may therefore represent the strongest magnetic fields in the Universe. The amplification occurs in the shear layer which forms between the neutron stars and on a time scale of only 1 millisecond, i.e. long before the remnant can collapse into a black hole.