TAPIR Seminar

Perturbed black holes relax by ringing with a characteristic spectrum of decaying oscillations. I will describe some of the unique features of the oscillations of rapidly rotating black holes. This includes a bifurcation of the frequency spectrum into distinct families of modes, long-lived collective excitations, and even the possibility of parametric resonance between modes. This parametric resonance leads to the excitation of further modes in a manner reminiscent of a transient, turbulent cascade, and has connections to the fluid-gravity correspondence. I will also discuss recent extensions of this work to nearly extremal, charged and rotating black holes, which reveals that these properties appear to be universal for nearly extremal black holes.