Quasinormal resonances of a massive scalar field in a near-extremal Kerr black hole spacetime

The fundamental resonances of near-extremal Kerr black holes due to massive scalar perturbations are derived analytically. We show that there exists a critical mass parameter, μc, below which increasing the mass μ of the field increases the oscillation frequency R(ω) of the resonance. On the other hand, above the critical field mass increasing the mass μ increases the damping rate I(ω) of the mode. We confirm our analytical results by numerical computations.