Polar quasinormal modes of the scalarized Einstein-Gauss-Bonnet black holes

We study the polar quasinormal modes of spontaneously scalarized black holes in Einstein-Gauss-Bonnet theory. In previous works we showed that a set of nodeless solutions of the fundamental branch of the model studied in [1] are stable under both radial [2] and axial perturbations [3]. Here we calculate the polar quasinormal modes and show that this set of solutions is stable against the polar perturbations as well. Thus for a certain region of the parameter space the scalarized black holes are potentially stable physically interesting objects. The spectrum of the polar quasinormal modes differs both quantitatively and qualitatively from the Schwarzschild one which offers the possibility to test the Gauss-Bonnet theory via the future gravitational wave observations.