Long-term GRMHD Simulations of Neutron Star Merger Accretion Disks

Neutron star mergers result in the formation of an accretion disk that evolves on timescales much longer than the orbital time, thereby ejecting mass that contributes to the r-process kilonova transient. It is widely accepted that angular momentum transport in astrophysical disks is mediated by magnetic turbulence, but thus far very few simulations of these disks have included this effect. I will present results of three-dimensional GRMHD simulations of neutron star merger accretion disks around Kerr black hole remnants, evolved for long enough to achieve completion of mass ejection far from the disk. Comparing to viscous hydrodynamic simulations, we find that inclusion of magnetic fields result in a factor of two more mass ejected, at higher velocities, and with a wider electron fraction. Given our initial magnetic field geometry, we also obtain a powerful relativistic jet capable of powering a short gamma-ray burst and its non-thermal afterglow.