Fluctuation, dissipation, and thermalization in nonequilibrium AdS ₅ black hole geometries

We give a simple recipe for computing dissipation and fluctuations (commutator and anticommutator correlation functions) for nonequilibrium black hole geometries. The recipe formulates Hawking radiation as an initial value problem, and is suitable for numerical work. We show how to package the fluctuation and dissipation near the event horizon into correlators on the stretched horizon. These horizon correlators determine the bulk and boundary field theory correlation functions. In addition, the horizon correlators are the components of a horizon effective action, which provides a quantum generalization of the membrane paradigm. In equilibrium, the analysis reproduces previous results on the Brownian motion of a heavy quark. Out of equilibrium, Wigner transforms of commutator and anticommutator correlation functions obey a fluctuation-dissipation relation at high frequency.