Improved effective-one-body description of coalescing nonspinning black-hole binaries and its numerical-relativity completion

TL;DR

This paper enhances the effective-one-body model for nonspinning black hole binaries by integrating recent analytical improvements and validating it against high-precision numerical relativity simulations across multiple mass ratios.

Contribution

The authors incorporate new analytical advances into the EOB model and accurately calibrate the main radial potential using NR data, achieving high-precision phase agreement.

Findings

EOB model matches NR data within 10^{-4} accuracy.

Good agreement for multiple multipoles without extra tuning.

Validated across mass ratios 1, 2, 3, 4, 6.

Abstract

We improve the effective-one-body (EOB) description of nonspinning coalescing black hole binaries by incorporating several recent analytical advances, notably: (i) logarithmic contributions to the conservative dynamics; (ii) resummed horizon-absorption contribution to the orbital angular momentum loss; and (iii) a specific radial component of the radiation reaction force implied by consistency with the azimuthal one. We then complete this analytically improved EOB model by comparing it to accurate numerical relativity (NR) simulations performed by the Caltech-Cornell-CITA group for mass ratios $q=(1,2,3,4,6)$. In particular, the comparison to NR data allows us to determine with high-accuracy ($\sim 10^{-4}$) the value of the main EOB radial potential: $A(u;\,\nu)$, where $u=GM/(R c^2)$ is the inter-body gravitational potential and $\nu=q/(q+1)^2$ is the symmetric mass ratio. We introduce a new technique for extracting from NR data an intrinsic measure of the phase evolution, ($Q_\omega(\omega)$ diagnostics). Aligning the NR-completed EOB quadrupolar waveform and the NR one at low frequencies, we find that they keep agreeing (in phase and amplitude) within the NR uncertainties throughout the evolution for all mass ratios considered. We also find good agreement for several subdominant multipoles without having to introduce and tune any extra parameters.