A New Code for Relativistic Magnetohydrodynamics in Dynamical Spacetimes

Several problems at the forefront of theoretical astrophysics require treatment of magnetic phenomena in full general relativity (GR). Such problems include the origin of gamma-ray bursts, magnetic braking of differential rotation in nascent neutron stars arising from stellar core collapse or binary merger, the formation of disks around newly-formed black holes, etc. To tackle these interesting, unsolved problems involving both GR and magnetohydrodynamics (MHD), we have developed a GR-MHD code capable of evolving magnetized fluids in dynamical spacetimes. We evolve the metric by integrating the BSSN equations, and use a high resolution shock capturing scheme to handle the MHD. We will describe the formulation of the coupled Einstein-Maxwell-MHD evolution equations and the algorithms used to integrate them. We will also present some code tests, giving particular attention to tests involving MHD waves induced by a gravitational wave.