Modelling Extreme Mass Ratio Binary Black Hole Inspirals
Consider a stellar-mass black hole (mass $\sim 10$ solar masses) in a
close orbit around a supermassive black hole (mass $\sim 10^6$ solar
masses). In this talk I'll discuss the challenge of trying to model
the orbital dynamics and gravitational-wave (GW) emission of such an
"EMRI" system as it evolves under the influence of the gravitational
radiation-reaction "self-force". Because of the highly asymmetric
mass ratio the orbital-decay timescale is much longer than the orbital
period, so a direct "numerical relativity" solution of the Einstein
equations would be both impractically expensive and insufficiently
accurate. Instead, we can use methods based on black hole perturbation
theory, treating the small black hole as a perturbation of a background
(Schwarzschild or Kerr) spacetime. I'll outline some of the analytical
and computational challenges of these analyses, describe recent
progress in surmounting these challenges, and discuss EMRI systems
as potential GW sources for the proposed eLISA/NGO space-based GW
observatory.
