Relativistic Effects on Triple Black Holes: Burrau's Problem Revisited

TL;DR

This study uses relativistic numerical simulations to analyze how mass and initial placement affect the evolution, mergers, and escapes of triple black hole systems, revealing a transition from escape to merger dominance at certain mass scales.

Contribution

It revisits Burrau's problem with relativistic corrections, providing new insights into the dynamics and outcomes of triple black hole systems across different mass ranges.

Findings

Higher black hole mass correlates with increased mergers.

System lifetimes decay exponentially with mass.

A significant fraction of systems eject supermassive black holes.

Abstract

We explore, using numerical simulations, the influence of mass and distance on the evolution of triple black hole systems. Following in the direction of Burrau's famous 3,4,5 problem, black holes are initially placed at the vertices of Pythagorean triangles. Numerical integration of orbits was conducted using relativistic corrections (post-Newtonian) up to the 2.5$^{th}$ order with ARCcode. As a descriptor of the evolution of the systems, the lifetimes, the number of two-body encounters and the number of mergers were all analysed. We found that as the mass unit of the black holes increased there was strong positive correlation with the fraction of mergers (0.9868), strong negative correlation with the average number of two-body encounters (-0.9016) and the average lifetimes of the triple systems decayed exponentially (determination coefficient of 0.9986). Around the mass unit range of 10$^{5.5}$M$_{\odot}$-10$^{5.6}$M$_{\odot}$, there was a transition from escape dominated dynamics to merger dominated dynamics. However, in the mass unit range of 10$^6$ M$_{\odot}$ $-$ 10$^{9}$M$_{\odot}$ with 1 pc distance unit, we find that 25\% of cases resulted in the escape of a supermassive black hole (SMBH) which may be a cause for wandering SMBH's found in some galaxies/galactic merger remnants.