Quasinormal modes of Reissner-Nordstrom-anti-de Sitter black holes: Scalar, electromagnetic, and gravitational perturbations

We study scalar, electromagnetic and gravitational perturbations of a Reissner-Nordstrom-anti-de Sitter (RN-AdS) spacetime, and compute its quasinormal modes (QNM's). We confirm and extend results previously found for Schwarzschild-anti-de Sitter (S-AdS) black holes. For large black holes, whose horizon is much larger than the AdS radius, different classes of perturbations are almost exactly isospectral; this isospectrality is broken when the black hole's horizon radius is comparable to the AdS radius. We provide very accurate fitting formulas for the QNM's, which are valid for large black holes having charge Q