Quasi-normal Modes of Electromagnetic Perturbations of Four-Dimensional   Topological Black Holes with Scalar Hair
  We study the perturbative behaviour of topological black holes with scalar hair. We calculate both analytically and numerically the quasi-normal modes of the electromagnetic perturbations. In the case of small black holes we find evidence of a second-order phase transition of a topological black hole to a hairy configuration. 
George Koutsoumbas, Suphot Musiri, Eleftherios Papantonopoulos, George   Siopsis