The response of black holes to small perturbations is known to be partially described by a superposition of quasinormal modes. Despite their importance to enable strong-field tests of gravity, little to nothing is known about what overtones and quasinormal-mode amplitudes are like for black holes in extensions to general relativity. We take a first step in this direction and study what is arguably the simplest model that allows first-principle calculations to be made: a nonrotating black hole in an effective-field-theory extension of general relativity with cubic-in-curvature terms. Using a phase-amplitude scheme that uses analytical continuation and the Prüfer transformation, we numerically compute, for the first time, the quasinormal overtone frequencies (in this theory) and quasinormal-mode excitation factors (in any theory beyond general relativity). We find that the overtone quasinormal frequencies and their excitation factors are more sensitive than the fundamental mode to the length scale introduced by the higher-derivative terms in the effective field theory. We argue that a description of all overtones cannot be made within the regime of validity of the effective field theory, and we conjecture that this is a general feature of any extension to general relativity that introduces a new length scale. We also find that a parametrization of the modifications to the general-relativistic quasinormal frequencies in terms of the ratio between and the black hole’s mass is somewhat inadequate, and we propose a better alternative. As an application, we perform a preliminary study of the implications of the breakdown, in the effective field theory, of the equivalence between the quasinormal mode spectra associated to metric perturbations of polar and axial parity of the Schwarzschild black hole in general relativity. We also present a simple justification for the loss of isospectrality. Published by the American Physical Society2024
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Enforcing Levy relaxation for multi-mode fibers with correlated disorder
Abstract Environmental perturbations and noise are source of mode mixing and interferences between the propagating modes of a complex multi-mode fiber (MMF). Typically, they are characterized by their correlation (paraxial) length, and their spectral content which describes the degree of coupling between various modes. We show that an appropriate control of these quantities allows to engineer Levy-type relaxation processes of an initial mode excitation. Our theory, based on random matrix theory modeling, is tested against realistic simulations with MMFs.
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- Award ID(s):
- 1641109
- PAR ID:
- 10390729
- Date Published:
- Journal Name:
- New Journal of Physics
- Volume:
- 24
- Issue:
- 5
- ISSN:
- 1367-2630
- Page Range / eLocation ID:
- 053012
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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