High accuracy simulations of black hole binaries:spins anti-aligned with the orbital angular momentum

TL;DR

This paper presents high-accuracy simulations of equal-mass binary black holes with anti-aligned spins, achieving precise gravitational waveforms and analyzing the effects of different constraint damping parameters.

Contribution

It introduces highly accurate binary black hole simulations with anti-aligned spins, improving waveform extraction and phase accuracy without phase shifts.

Findings

Waveforms have phase errors less than 0.1 radians without shifts.

Extrapolated waveforms differ by up to 0.13 radians in phase from finite-radius extraction.

Constraint damping choices significantly reduce junk radiation and improve waveform quality.

Abstract

High-accuracy binary black hole simulations are presented for black holes with spins anti-aligned with the orbital angular momentum. The particular case studied represents an equal-mass binary with spins of equal magnitude S/m^2=0.43757 \pm 0.00001. The system has initial orbital eccentricity ~4e-5, and is evolved through 10.6 orbits plus merger and ringdown. The remnant mass and spin are M_f=(0.961109 \pm 0.000003)M and S_f/M_f^2=0.54781 \pm 0.00001, respectively, where M is the mass during early inspiral. The gravitational waveforms have accumulated numerical phase errors of <~ 0.1 radians without any time or phase shifts, and <~ 0.01 radians when the waveforms are aligned with suitable time and phase shifts. The waveform is extrapolated to infinity using a procedure accurate to <~ 0.01 radians in phase, and the extrapolated waveform differs by up to 0.13 radians in phase and about one percent in amplitude from the waveform extracted at finite radius r=350M. The simulations employ different choices for the constraint damping parameters in the wave zone; this greatly reduces the effects of junk radiation, allowing the extraction of a clean gravitational wave signal even very early in the simulation.