Quasinormal modes of nonlinear electromagnetic black holes from unstable null geodesics

Abstract

The expressions for the quasinormal modes (QNMs) of black holes with nonlinear electrodynamics, calculated in the eikonal approximation, are presented. In the eikonal limit QNMs of

Scattering and absorption sections of nonlinear electromagnetic black holes

“…In [10] the quasinormal modes of black holes were studied with nonlinear electrodynamics in the eikonal approximation and the way the effective metric modifies the equation of motion for a test particle in the static spherically symmetric (SSS) space time and expressions the Lyapunov exponent.…”

Electromagnetic perturbations of black holes in general relativity coupled to nonlinear electrodynamics

“…One of the special properties of the NED field is that in such a field photon does not follow the null geodesics of the background spacetime metric anymore, instead, it propagates along the null geodesics of an effective metric which is characterized by the non-linearities of the field [18][19][20][21][22][23].…”

Electromagnetic perturbations of black holes in general relativity coupled to nonlinear electrodynamics: Polar perturbations

“…In that paper we showed that i) the axial EM perturbations of in the NED BHs give different potentials and, consequently, different QNM spectra, in comparison with those related to the RN BHs governed by the standard LED, since it is well known from Refs. [17][18][19] that the QNMs of the EM perturbations of the electrically and magnetically charged RN BHs are isospectral, with identical effective potentials; ii) in the eikonal (large multipole numbers) regime, the QNMs of the NED BHs are determined by the unstable circular photon orbits determined by the given geometry, i.e., by unstable circular null geodesics determined by the effective (or optical) geometry, since in the NED light ray does not follow the null geodesics of the spacetime [20][21][22][23][24][25][26][27]. It should be noted that one of the outstanding pioneering works devoted to the study of the perturbations of the one-parameter family of Lagrangian densities that yields static, spherically symmetric magnetically charged BH solutions in the NED is the paper [18] that overlaps some important results of the present paper and Ref.…”