Production of EMRIs in supermassive black hole binaries

Abstract

We consider the formation of extreme mass-ratio inspirals (EMRIs) sourced from a stellar cusp centred on a primary supermassive black hole (SMBH) and perturbed by an inspiraling less massive secondary SMBH. The problem is approached numerically, assuming the stars are non-interacting over these short time-scales and performing an ensemble of restricted three-body integrations. From these simulations, we see that not only can EMRIs be produced during this process, but the dynamics are also quite rich. In particular, most of the EMRIs are produced through a process akin to the Kozai-Lidov mechanism, but with strong effects due to the non-Keplerian stellar potential, general relativity and non-secular oscillations in the angular momentum on the orbital time-scale of the binary SMBH system. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.