PSEUDOSPECTRAL APPARENT HORIZON FINDERS - AN EFFICIENT NEW ALGORITHM

We review the problem of finding an apparent horizon in Cauchy data (S igma,g(ab),K-ab) in three space dimensions without symmetries. We desc ribe a family of algorithms which includes the pseudospectral apparent horizon finder of Nakamura et al. and the curvature flow method propo sed by Tod as special cases. We suggest that other algorithms in the f amily may combine the speed of the former with the robustness of the l atter. A numerical implementation for Cauchy data given on a grid in C artesian coordinates is described, and tested on Brill-Lindquist and K err initial data. The new algorithm appears faster and more robust tha n previous ones.