Close Encounter of Three Black Holes III (2406.11985v1)

Abstract: We revisit the three black hole scenario with numerical relativity techniques to study hierarchical configurations where the inner binary contains highly spinning black holes. We find that the merger time of the binary gets a delay (with a number of orbits to merger increase), depending strongly with the distance to the orbiting third hole $D$ as $\sim1/D^{1.6\pm0.1}$. Notably, a different dependence from what we had found in the nonspinning case, $\sim1/D^{2.5}$. We interpret this effect as mostly due to a spin-orbit coupling between the third hole and the closest member of the binary in the successive approaches. This lead us next to study scattering configurations of the third hole with the binary in order to evaluate the extent of this ``sudden'' interactions, finding also a correlation of the delay in merger times with the closest distance, even for the nonspinning cases. We then explore the mass ratio dependence of the triple system by modeling binaries orbiting a larger black hole bearing masses ratios 8:1:1 and 18:1:1 in co-orbiting or counter-orbiting configurations, finding merger times increasing with increasing mass ratios and for the counter-orbiting cases.