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Description
We explore the quasinormal modes of a massless test scalar field in the gravitational background of a non-extremal dilatonic dyonic black hole. The dyon-like black hole solution is considered within a four-dimensional gravitational model that includes two scalar fields and two 2-forms.
It is governed by two dilatonic coupling vectors (\vec{\lambda}_s) (with (s=1,2)) that satisfy (\vec{\lambda}_1 = \vec{\lambda}_2 = \vec{\lambda}) and (\vec{\lambda}^2 = 1/2). We derive and examine the quasinormal modes of a massless scalar test field in the eikonal limit.
These modes are governed by the solution parameters $\mu > 0$, $P_1 > 0$, and $P_2 > 0$. In the two limiting scenarios -- namely $P_1 = P_2 = 0$ and $P_1 = P_2 = P > 0$ -- our results reduce exactly to the known (eikonal) quasinormal spectra for the Schwarzschild and Reissner-Nordström black holes, respectively.
Numerical higher-order WKB analysis of quasinormal frequencies for two lower levels (for various values of parameters) is also presented.
