Tetrad formalism for numerical relativity on conformally compactified constant mean curvature hypersurfaces

Understand

We present a new evolution system for Einstein's field equations which is based on tetrad fields and conformally compactified hyperboloidal spatial hypersurfaces which reach future null infinity.

• The boost freedom in the choice of the tetrad is fixed by requiring that its timelike leg be orthogonal to the foliation, which consists of constant mean curvature slices.
• The rotational freedom in the tetrad is fixed by the 3D Nester gauge.
• With these conditions, the field equations reduce naturally to a first-order constrained symmetric hyperbolic evolution system which is coupled to elliptic equations for the gauge variables.