Relativistic effects on triple black holes: Burrau’s problem revisited

Abstract

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 2.5th 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 105.5–105.6M⊙, there was a transition from escape dominated dynamics to merger dominated dynamics. However, in the mass unit range of 106–109M⊙ with 1 pc distance unit, we find that 25 per cent 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.