Multipolar analysis of spinning binaries

Abstract

We present a preliminary study of the multipolar structure of gravitational radiation from spinning black hole binary mergers. We consider three different spinning binary configurations: (1) one ‘hang-up’ run, where the black holes have equal masses and large spins initially aligned with the orbital angular momentum; (2) seven ‘spin-flip’ runs, where the holes have a mass ratio q ≡ M1/M2 = 4, the spins are anti-aligned with the orbital angular momentum, and the initial Kerr parameters of the holes j1 = j2 = ji (where j ≡ J/M2) are fine-tuned to produce a Schwarzschild remnant after merger; (3) three ‘super-kick’ runs where the mass ratio q = 1, 2, 4 and the spins of the two holes are initially located on the orbital plane, pointing in opposite directions. For all of these simulations we compute the multipolar energy distribution and the Kerr parameter of the final hole. For the hang-up run, we show that including leading-order spin–orbit and spin–spin terms in a multipolar decomposition of the post-Newtonian waveforms improves agreement with the numerical simulation.