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Title: Linear stability analysis of hairy black holes in degenerate higher-order scalar-tensor theories ||
Abstract: I talk about static spherically symmetric black hole solutions and their linear stability in the shift- and reflection-symmetric subclass of quadratic degenerate higher-order scalar-tensor (DHOST) theories. Black holes in this class of theories can support a nontrivial scalar hair, which depends linearly on time. I derive the background field equations for a generic theory within this class and show that they can be reduced to a simple system of lower-order differential equations. We then consider odd-parity perturbations about the black hole solutions and derive concise criteria for the black holes to be stable. ||