Quasinormal modes of a nonsingular spherically symmetric black hole effective model with holonomy corrections

We calculate the quasinormal modes of a nonsingular spherically symmetric black hole effective model with holonomy corrections. The model is based on quantum corrections inspired by loop quantum gravity. It is covariant and results in a spacetime that is regular everywhere with a parameter-dependent black bounce. Perturbations of these black holes due to massless scalar and electromagnetic fields have been previously calculated, and some intriguing results were observed. For some modes, the frequency versus minimum-radius parameter trajectories were found to spiral and self-intersect in the complex plane. In addition, the spectrum of overtones has real frequencies that oscillate with increasing overtone number and may even vanish for some overtones. We have calculated the quasinormal modes for all massless spin perturbations, including spin-$1/2$ and axial- and polar-gravitational. We find that the trajectory spirals are restricted to scalar perturbations and observe some interesting overtone behavior for gravitational perturbations. The amount of isospectrality violation in the gravitational quasinormal mode spectra is also examined.