Speaker
Description
Black holes provide unique laboratories for testing gravity in the strong-field regime. The ringdown phase of a merger is particularly valuable, as it encodes the quasi-normal modes (QNMs) of the remnant black hole. In general relativity, these modes depend only on the mass and spin, making them powerful probes of the no-hair theorem. Modified gravity can alter this spectrum, offering potential observational signatures of new physics. Among such theories, Einstein–scalar–Gauss–Bonnet (EsGB) gravity is especially interesting: it predicts the spontaneous scalarization of black holes and the breaking of isospectrality, leading to a characteristic mode doublet in the ringdown.
In this seminar, I will present my master’s thesis project on the quasi-normal modes of black holes in EsGB gravity. Using axisymmetric numerical simulations of perturbed black holes, I extract the ringdown signal and disentangle the contributing modes. This setup, while simpler than a full binary merger, captures the essential physics of the ringdown and allows for high-resolution studies that are necessary to resolve subtle effects such as the mode doublet. By comparing numerical results with perturbative predictions, I also investigate the role of nonlinear phenomena such as quadratic modes, and assess where perturbation theory begins to break down in the small-coupling limit of the theory.