Year: 2025
Type: dissertation
Abstract: Black holes are among the most fascinating astrophysical objects in our universe. They are a key feature of general relativity, Albert Einstein's theory of gravity. The detection of gravitational waves provides a new way to study black holes. Since the first detection of gravitational waves, in 2015, from the merger of two black holes, hundreds of signals from black-hole mergers have been detected. After the merger, the newly formed black black hole relaxes through the ringdown and the surrounding spacetime rings with the black hole's quasinormal modes. General relativity predicts that the quasinormal modes of a Kerr black hole have frequencies that are fully determined by the black hole's mass and spin. To study what happens when general relativity is modified, we need to know how black holes and their quasinormal modes behave under such modifications. In this thesis we find the quasinormal modes of rapidly rotating black holes in higher-derivative gravity, an effective-field-theory extension of general relativity. This is achieved by reducing the equations for curvature perturbations to a system of decoupled equations that form a set of modified Teukolsky equations. The leading effect of such small deviations in the effective potential of the Teukolsky equation on quasinormal mode frequencies is precisely computed. We construct a waveform template for the ringdown of black hole mergers that includes the effect of higher-derivative corrections to the spectrum of quasinormal modes valid for all spins and accounts for isospectrality breaking. The analysis of all gravitational wave events with a detectable ringdown yields no evidence of higher-derivative corrections and we set an upper bound on the effective length scale for higher-derivative corrections to general relativity.
Source: Lirias
Author: Maenaut, Simon
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W7113587785
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