Thermal spectral functions of strongly coupled N=4 supersymmetric Yang-Mills theory

We use the gauge-gravity duality conjecture to compute spectral functions of the stress-energy tensor in finite-temperature N=4 supersymmetric Yang-Mills theory in the limit of large N-c and large 't Hooft coupling. The spectral functions exhibit peaks characteristic of hydrodynamic modes at small frequency, and oscillations at intermediate frequency. The nonperturbative spectral functions differ qualitatively from those obtained in perturbation theory. The results may prove useful for lattice studies of transport processes in thermal gauge theories.