Ameliorating the Courant Limitations of Spherical Coordinates in Numerical Simulations of the Einstein Equations

Explicit schemes for the evolutions of hyperbolic systems in spherical coordinates have the well known Courant (CFL) limitation that the maximum stable timestep scales as dt ~ dr dtheta dphi. In this talk, we compare a variety of methods we used to significantly increase the size of the timestep BSSN simulations using spherical coordinates while maintaining high accuracy. For our methods, the timestep scales as dt ~ dr.