Ergoregion instability of exotic compact objects: Electromagnetic and gravitational perturbations and the role of absorption

  title={Ergoregion instability of exotic compact objects: Electromagnetic and gravitational perturbations and the role of absorption},
  author={Elisa Maggio and Vitor Cardoso and Sam R. Dolan and Paolo Pani},
  journal={Physical Review D},
Spinning horizonless compact objects may be unstable against an ``ergoregion instability.'' We investigate this mechanism for electromagnetic perturbations of ultracompact Kerr-like objects with a reflecting surface, extending previous (numerical and analytical) work limited to the scalar case. We derive an analytical result for the frequency and the instability timescale of unstable modes which is valid at small frequencies. We argue that our analysis can be directly extended to gravitational… 

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