Ultimate Black Hole Recoil: What the maximum high energy collisions kick is?

TL;DR

This study uses extensive numerical simulations of black hole mergers to estimate the maximum recoil velocity, approaching 10% of the speed of light, by exploring various spin configurations and extrapolating to extremal spins.

Contribution

It provides the first comprehensive numerical estimate of the maximum black hole recoil velocity near the speed of light for specific spin configurations.

Findings

Maximum recoil velocity estimated at approximately 28,562 km/s.

Recoil velocity approaches 10% of the speed of light for extremal spins.

Extensive simulations covering various spin orientations and impact parameters.

Abstract

We performed a series of 1381 full numerical simulations of high energy collision of black holes to search for the maximum recoil velocity after their merger. We consider equal mass binaries with opposite spins pointing along their orbital plane and perform a search of spin orientations, impact parameters, and initial linear momenta to find the maximum recoil for a given spin magnitude $s$. This spin sequence for $s=0.4, 0.7, 0.8, 0.85, 0.9$ is then extrapolated to the extreme case, $s=1$, to obtain an estimated maximum recoil velocity of $28,562\pm 342$ km/s, thus approximately bounded by $10\%$ the speed of light.