Quasinormal modes of Kerr-like black bounce spacetime

Abstract

We investigate the quasinormal mode (QNM) spectrum of a Kerr-like black-bounce spacetime under massive scalar-field perturbations. Starting from the Kerr-like deformation of the Simpson--Visser black-bounce geometry, we derive the corresponding radial and angular equations and obtain the effective potential governing scalar perturbations. We show that the Kerr-like black-bounce spacetime inherits a characteristic double-peaked effective potential, analogous to the Schwarzschild-like black-bounce case, which is known to be associated with late-time echo signals. The QNM frequencies are computed by means of the P\"oschl--Teller potential approximation and the semi-analytic WKB method (up to sixth order), and we demonstrate good agreement between these two approaches. We then analyze in detail how the QNM spectrum depends on the spin parameter $a$, the bounce parameter $p$ that interpolates between black-hole and wormhole geometries, and the scalar-field mass $\mu$. Our results indicate that increasing either $a$ or $p$ lowers both the real frequency and the magnitude of the imaginary part, leading to longer-lived modes. Moreover, the mass of the scalar field has a non-negligible impact on the ringdown spectrum. These features suggest that rotating black-bounce geometries may leave distinct imprints in the ringdown phase of gravitational-wave signals, and motivate future studies of echoes and parameter estimation in the context of present and upcoming detectors.