Instabilities in Kerr Spacetimes
  We present a generalization of previous results regarding the stability under gravitational perturbations of nakedly singular super extreme Kerr spacetime and Kerr black hole interior beyond the Cauchy horizon. To do so we study solutions to the radial and angular Teukolsky's equations with different spin weights, particulary $s=\pm 1$ representing electromagnetic perturbations, $s=\pm 1/2$ representing a perturbation by a Dirac field and $s=0$ representing perturbations by a scalar field.   By analizing the properties of radial and angular eigenvalues we prove the existence of an infinite family of unstable modes. 
Gustavo Dotti, Reinaldo J. Gleiser, Ignacio F. Ranea-Sandoval
gr-qc