The initial boundary value problem for free-evolution formulations of General Relativity

Understand

We consider the initial boundary value problem for free-evolution formulations of general relativity coupled to a parametrized family of coordinate conditions that includes both the moving puncture and harmonic gauges.

• We concentrate primarily on boundaries that are geometrically determined by the outermost normal observer to spacelike slices of the foliation.
• We present high-order-derivative boundary conditions for the gauge, constraint violating and gravitational wave degrees of freedom of the formulation.
• Second order derivative boundary conditions are presented in terms of the conformal variables used in numerical relativity simulations.