Year: 2020
Type: dissertation
Abstract: The nonlinear dynamics of black holes is an increasingly relevant topic of which little \nis known. In this thesis, we study the full nonlinear dynamics of black holes, as well as \ntheir linear behavior, and combine them to find a comprehensive picture of the processes \ninvolved. In particular, we study the dynamics of unstable black holes in asymptotically \nanti-de Sitter spacetimes. We study their general behavior and approach to the final \nequilibrium state. In the first part of this work, we present linear studies of charged \nscalar field perturbations of Reissner-Nordstrom anti-de Sitter (RN-AdS) black holes in \nthe small and large black hole regimes. We present their quasinormal mode spectra, identify \nthe known mode families—superradiant modes, zero-damped modes, AdS modes, and \nthe near-horizon mode— and track their migration under variation of the black hole and \nfield parameters. We present results of the full nonlinear studies of perturbed small and \nlarge RN-AdS, showing the nonlinear development of the unstable superradiant modes. \nFor generic initial conditions, charge and mass are transferred from the black hole to the \nscalar field, until an equilibrium solution with a scalar condensate is reached. Additionally, \nwe use the results from the linear analysis to construct special initial data corresponding \nto an unstable overtone mode. We find that these special data evolve to produce a new \nequilibrium state, an excited hairy black hole with the scalar condensate in an overtone \nconfiguration. This state is, however, unstable, and the system eventually decays to the \ngeneric end state. This demonstrates the potential relevance of overtone modes as transients \nin black hole dynamics. In the second part of this work, we present linear and \nnonlinear studies of a planar Schwarzschild-AdS black hole and two massive scalar fields. \nAbove the critical energy density the system reaches an equilibrium state where one of the \nscalars forms a condensate and the other vanishes. Below the critical energy density, how- \never, the system displays an instability at the linear regime. We present results of the full \nnonlinear development of this instability where a suitable equilibrium condensate does not \nexist. Indeed, we present compelling evidence that during the dynamics arbitrarily large \ncurvatures are uncovered in the vicinity of the horizon, which turn such region singular in \nfinite time with respect to the boundary observer.
Source: UWSpace (University of Waterloo)
Author: Pablo Bosch Gomez
Language: English
Subfield: Nuclear and High Energy Physics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
OpenAlex ID: W3094549325