Total recoil: the maximum kick from nonspinning black-hole binary inspiral

TL;DR

This study uses advanced numerical relativity simulations to measure the maximum recoil velocity of non-spinning black-hole binaries during merger, revealing a significant astrophysical kick of up to approximately 175 km/s.

Contribution

It provides the largest parameter study to date on non-spinning black-hole binary mergers, accurately quantifying recoil velocities and final spins across various mass ratios.

Findings

Maximum recoil velocity of 175.2 km/s for specific mass ratio.

Recoil velocity depends on mass ratio and asymmetry.

Final spins are measured with 2% accuracy.

Abstract

When unequal-mass black holes merge, the final black hole receives a ``kick'' due to the asymmetric loss of linear momentum in the gravitational radiation emitted during the merger. The magnitude of this kick has important astrophysical consequences. Recent breakthroughs in numerical relativity allow us to perform the largest parameter study undertaken to date in numerical simulations of binary black hole inspirals. We study non-spinning black-hole binaries with mass ratios from $q=M_1/M_2=1$ to $q =0.25$ ($\eta = q/(1 + q)^2$ from 0.25 to 0.16). We accurately calculate the velocity of the kick to within 6%, and the final spin of the black holes to within 2%. A maximum kick of $175.2\pm11$ km s$^{-1}$ is achieved for $\eta = 0.195 \pm 0.005$.