Recent Developments

The Caltech-Cornell collaboration has produced a computer code which can simulate the motion of pairs of black holes or neutron stars with very high accuracy, and great computational efficiency. While the code cannot yet simulate the final merger, efforts are under way to push the code further. Meanwhile, SXS members continue to extract scientific information from the simulations.

Boundary Conditions

SXS members have used very large and highly accurate simulations to test various types of boundary conditions for relativistic simulations. They have compared freezing, Sommerfeld, and Kreiss-Winicour constraint-preserving boundary conditions, along with sponge layers and spatial compactification. They report their results in a recent paper.

Constraint Damping

Caltech grad student Rob Owen has developed a new formulation of Einstein's equations. His system generalizes the KST system, to include constraint-damping terms, while preserving hyperbolicity of the evolution equations.

Hydrodynamics

Members of the Cornell group have been developing techniques to combine the accuracy of spectral techniques used to simulate spacetime with the robustness of finite differencing methods to simulate fluids—such as neutron stars. The report on their ideas in this paper.