Instability in charged Gauss-Bonnet-de Sitter black holes

We study the instability of the charged Gauss-Bonnet-de Sitter black holes under gravito-electromagnetic perturbations. We adopt two criteria to search for an instability of the scalar type perturbations, including the local instability criterion based on the AdS(2) Breitenlohner-Freedman (BF) bound at extremality and the dynamical instability via quasinonnal modes by full numerical analysis. We uncover the gravitational instability in five spacetime dimensions and above, and construct the complete parameter space in terms of the ratio of event and cosmological horizons and the Gauss-Bonnet coupling. We show that the BF bound violation is a sufficient but not necessary condition for the presence of dynamical instability. While the physical origin of the instability without the Gauss-Bonnet term has been argued to be from the AdS, BF bound violation, our analysis suggests that the BF bound violation cannot account for all physical origin of the instability for the charged Gauss-Bonnet black holes.

Automated summary

This study investigates the instability of charged Gauss-Bonnet-de Sitter black holes under gravito-electromagnetic perturbations. The research uncovers gravitational instability in spacetime dimensions five and above and constructs the complete parameter space. Additionally, it suggests that the BF bound violation cannot fully account for the physical origin of instability in charged Gauss-Bonnet black holes.