Gravity Waves from Extreme-Mass-Ratio Plunges into Kerr Black Holes
  Massive objects orbiting a near-extreme Kerr black hole quickly plunge into the horizon after passing the innermost stable circular orbit. The plunge trajectory is shown to be related by a conformal map to a circular orbit. Conformal symmetry of the near-horizon region is then used to compute the gravitational radiation produced during the plunge phase. 
Shahar Hadar, Achilleas P. Porfyriadis, Andrew Strominger
hep-th astro-ph.HE gr-qc