Linear instability of charged massless scalar perturbation in regularized 4D charged Einstein-Gauss-Bonnet anti de-Sitter black holes

We study the linear instability of the charged massless scalar perturbation in regularized 4D charged Einstein-Gauss-Bonnet-AdS black holes by exploring their quasinormal modes.We find that the linear instability is triggered by superradiance.The charged massless scalar perturbation becomes more unstable with increasing Gauss-Bonnet coupling constant or black hole charge.Decreasing the AdS radius,on the other hand,will make the charged massless scalar perturbation more stable.The stable region in parameter space(α,Q,Λ)is given.Moreover,we find that the charged massless scalar perturbation is more unstable for larger scalar charge.The modes of multipoles are more stable than that of the monopole.     

Instability of regularized 4D charged Einstein-Gauss-Bonnet de-Sitter black holes

We studied the instability of regularized 4D charged Einstein-Gauss-Bonnet de-Sitter black holes under charged scalar perturbations.The unstable modes satisfy the superradiant condition,but not all of the modes satisfying the superradiant condition are unstable.The instability occurs when the cosmological constant is small and the black hole charge is not too large.The Gauss-Bonnet coupling constant further destabilizes black holes when both the black hole charge and the cosmological constant are small and further stabilizes black holes when the black hole charge is large.