Quasi-normal modes of AdS black holes and RHIC

I calculate analytically low frequency quasi-normal modes of gravitational perturbations of AdS Schwarzschild black holes. I arrive at analytic expressions which are in agreement with their counterparts from linearized hydrodynamics, in accordance with the AdS/CFT correspondence. The results are also in good agreement with results of numerical calculations. I discuss their relevance to the quark-gluon plasma formed in heavy ion collisions at RHIC.