Date of Award

May 2019

Degree Type


Degree Name

Doctor of Philosophy (PhD)




Duncan A. Brown


Black holes, gravitational waves, Kerr Metric, LIGO, quasi-normal-modes, ringdown

Subject Categories

Physical Sciences and Mathematics


In this thesis, we study black hole ringdowns as a probe to understand the strong-field clssical gravity. When two black holes merge, they form a single distorted black hole that then radiates gravitational waves and settles into a final stable Kerr state. The signal produced during this process is called the ringdown and can be modelled as perturbations on the space-time of the final Kerr black hole. Ringdowns contain information about the strong field dynamics close to the black holes and thus, can be used to test our understanding of gravity. There are three specific questions that we explore in this thesis: First, at what point after the merger of two black holes can one use a perturbative description to model the space-time? This tells where in the gravitational wave signal of a binary black hole merger can one start a ringdown-based test. Second, how likely are we to realistically find a signal that allows us to perform a ringdown-based test given the current and future gravitational wave observatories. And finally we discuss, how should the data analysis be carried out in order to extract information from the ringdown of an observed GW signal?


Open Access