Eccentricity Reduction for Quasicircular Binary Evolutions

Understand

Simulation of quasicircular compact binaries is a major goal in numerical relativity, as they are expected to constitute most gravitational wave observations.

• However, given that orbital eccentricity is not well-defined in general relativity, providing initial data for such binaries is a challenge for numerical simulations.
• Most numerical relativity codes obtain initial conditions for low-eccentricity binary simulations by iterating over a sequence of short simulations -- measuring eccentricity mid-evolution and correcting the initial data parameters accordingly.
• Eccentricity measurement depends on a numerically challenging nonlinear fit to an estimator model, and the resulting eccentricity estimate is extremely sensitive to small changes in how the fit is performed.