Response of a Kerr black hole to a generic tidal perturbation (2412.15117v1)

Abstract: We derive the response of non-extremal as well as extremal Kerr black holes (BHs) to generic tidal perturbations. The real part of the tidal response provides the tidal Love numbers (TLNs). Our results suggest that the static as well as dynamical (linear-in-frequency) TLNs vanish for both Schwarzschild and slowly rotating Kerr BHs, under generic perturbations. The vanishing of static and dynamical TLNs also holds for axi-symmetric tidal perturbations of non-extremal and extremal Kerr BHs. In fact, even under generic tidal perturbations the static TLNs of non-extremal and extremal Kerr BHs vanish identically. The only case where TLNs do not vanish is when they are dynamical and arise in response to generic tidal perturbations of non-extremal and extremal Kerr BHs. We also discuss the symmetries of the non-zero dynamical TLNs for both non-extremal and extremal Kerr BHs, under the change of sign of the spin, for electromagnetic and gravitational perturbations.