Horizon instability of extremal Reissner-Nordstr\"om black holes to charged perturbations

Understand

We investigate the stability of highly charged Reissner-Nordstr\"om black holes to charged scalar perturbations.

• We show that the near-horizon region exhibits a transient instability which becomes the Aretakis instability in the extremal limit.
• The rates we obtain match the enhanced rates for nonaxisymmetric perturbations of the near-extremal and extremal Kerr solutions.
• The agreement is shown to arise from a shared near-horizon symmetry of the two scenarios.