Horizon-absorption effects in coalescing black-hole binaries: An effective-one-body study of the non-spinning case

TL;DR

This study compares numerical and analytical models of horizon absorption in non-spinning black hole binaries, demonstrating high agreement and assessing its impact on gravitational wave detection across various mass ratios.

Contribution

It introduces an improved EOB model incorporating horizon absorption effects and evaluates their significance for gravitational wave observations.

Findings

Horizon fluxes agree within a few percent between models up to late plunge.

Horizon absorption has negligible impact on waveform detection for certain mass ratios.

The upgraded EOB model accurately captures horizon effects across a wide range of binary parameters.

Abstract

We study the horizon absorption of gravitational waves in coalescing, circularized, nonspinning black hole binaries. The horizon absorbed fluxes of a binary with a large mass ratio (q=1000) obtained by numerical perturbative simulations are compared with an analytical, effective-one-body (EOB) resummed expression recently proposed. The perturbative method employs an analytical, linear in the mass ratio, effective-one-body (EOB) resummed radiation reaction, and the Regge-Wheeler-Zerilli (RWZ) formalism for wave extraction. Hyperboloidal (transmitting) layers are employed for the numerical solution of the RWZ equations to accurately compute horizon fluxes up to the late plunge phase. The horizon fluxes from perturbative simulations and the EOB-resummed expression agree at the level of a few percent down to the late plunge. An upgrade of the EOB model for nonspinning binaries that includes horizon absorption of angular momentum as an additional term in the resummed radiation reaction is then discussed. The effect of this term on the waveform phasing for binaries with mass ratios spanning 1 to 1000 is investigated. We confirm that for comparable and intermediate-mass-ratio binaries horizon absorbtion is practically negligible for detection with advanced LIGO and the Einstein Telescope (faithfulness greater than or equal to 0.997).