Precessing Binary Black Holes Simulations: Quasicircular Initial Data

TL;DR

This paper introduces fitting formulas for initial data parameters in precessing binary black hole simulations, enabling precise control of orbital eccentricity and prediction of merger times without extensive trial-and-error evolutions.

Contribution

The authors develop and validate fitting formulas that accurately set initial parameters for precessing BBH simulations, reducing computational costs and improving control over orbital eccentricity and merger timing.

Findings

Fitting formulas achieve eccentricity $ extless 10^{-4}$ in 729 configurations.

Formulas predict the number of orbits to merger with high accuracy.

No extensive exploratory evolutions needed for desired initial conditions.

Abstract

In numerical evolutions of binary black holes (BBH) it is desirable to easily control the orbital eccentricity of the BBH, and the number of orbits completed by the binary through merger. This paper presents fitting formulae that allow to choose initial-data parameters for generic precessing BBH resulting in an orbital eccentricity $\sim 10^{-4}$, and that allow to predict the number of orbits to merger. We further demonstrate how these fits can be used to choose initial-data parameters of desired non-zero eccentricity. For both usage scenarios, no costly exploratory BBH evolutions are necessary, but both usage scenarios retain the freedom to refine the fitted parameters further based on the results of BBH evolutions. The presented fitting formulas are based on 729 BBH configurations which are iteratively reduced to eccentricity $\lesssim 10^{-4}$, covering mass-ratios between 1 and 8 and spin-magnitude up to 0.5. 101 of these configurations are evolved through the BBH inspiral phase.