Stealth black hole perturbations in kinetic gravity braiding

Abstract

We study stealth black hole perturbations in shift symmetric kinetic gravity braiding and obtain its analogous Regge–Wheeler and Zerilli master equations for the odd and even parity sectors. We show that the nontrivial hair of static and spherically symmetric stealth black holes contributes only an additional source term to the even parity master equation. Furthermore, we derive exact solutions to the monopolar and dipolar perturbations and show that they are generally pathological non-gauge modes or else reduce to the pure-gauge low-order multipoles of general relativity.

Disformal map and Petrov classification in modified gravity

“…With this vast landscape of exact solutions, it becomes crucial to find methods to classify them and characterize their physical properties. To a large extent, most of the investigations have focused on perturbative analysis of black hole and cosmological stealth solutions, revealing crucial information on the quasinormal modes as well as the issues of the strong coupling [75][76][77][78][79][80][81][82][83][84][85]. However, some key information about these solutions can be revealed only by mean of non-perturbative methods, such as the nature of their principal null directions (PNDs), which in turn, is intimately related to the non-perturbative gravitational waves carried in the non-stationary regime.…”