Gravitational Quasinormal Modes and Grey-Body Factors of Bonanno-Reuter Regular Black Holes

Abstract: We study gravitational perturbations of the Bonanno--Reuter quantum-corrected black hole arising in the asymptotic safety scenario, focusing on QNMs and grey-body factors. Assuming the RG parameter $\tilde{\omega}$ is fixed to its phenomenologically motivated value, we treat the interpolation parameter $\gamma$ as free and investigate how it modifies the black hole's response to axial gravitational perturbations. Quasinormal frequencies are computed using the sixth-order WKB method with Pad\'e approximants, and their dependence on $\gamma$ and the black hole mass $M$ is analyzed. We find that the Schwarzschild limit is rapidly recovered for large $M$ or large $\gamma$, while significant deviations arise in the quantum regime. The accuracy of the WKB results is confirmed by time-domain integration of the wave equation. Comparison of grey-body factors computed via both the WKB method and the quasinormal mode correspondence are in a good concordance. Our findings indicate that quantum corrections can leave significant imprints in the ringdown and radiation spectra, while preserving consistency with classical results in the appropriate limit.