Anomalous decay rate of quasinormal modes in Reissner-Nordström black holes (2011.10620v3)

Abstract: The anomalous decay rate of the quasinormal modes occurs when the longest-lived modes are the ones with higher angular number. Such behaviour has been recently studied in different static spacetimes, for scalar and fermionic perturbations, being observed in both cases. In this work, we extend the existent studies to the charged spacetimes, namely, the Reissner-Nordstr\"om, the Reissner-Nordstr\"om-de Sitter and the Reissner-Nordstr\"om-Anti-de Sitter black holes. We show that the anomalous decay rate behaviour of the scalar field perturbations is present for every charged geometry in the photon sphere modes, with the existence of a critical scalar field mass whenever $\Lambda \geq 0$. In general, this critical value of mass increases with the raise of the black hole charge, thus rendering a minimum in the Schwarzschild limit. We also study the dominant mode/family for the massless and massive scalar field in these geometries showing a non-trivial dominance of the spectra that depends on the black hole mass and charge.