The scientific exploitation of gravitational wave observations depends strongly on the models of the signals that we use for their detection, mainly for binary black holes. These models, known as waveform models, are obtained from Einstein's equations (or their equivalent in alternative theories of gravity). The way of obtaining them is via different perturbative schemes and/or numerical...
Conformal geometry tools allow us to study global geometric aspects of a spacetime using local differential geometry. In this talk, I will focus on a particular conformal representation of Minkowski spacetime which allows us to study the asymptotics of massless fields near spatial infinity. I will briefly discuss the analysis of the asymptotics of the wave equation in the context of this...
Euclidean wormholes are exotic types of gravitational solutions that still challenge our physical intuition and understanding. After reviewing universal properties of asymptotically AdS wormhole solutions from a gravitational (bulk) point of view and the paradoxes they raise, I will describe some concrete (microscopic) field theoretic setups and models that exhibit such properties. These...
Three dimensional gravity in Fefferman-Graham or BMS gauge is entirely described by the coadjoint representation of its asymptotic symmetry group. A group-theoretical attempt at quantization requires one to quantize not only individual but the whole collection of coadjoint orbits. This is where model spaces come in. We propose a definition of a model space for generic Lie groups in terms of...
Scattering problems in black hole interiors are an indispensable tool in the study of strong cosmic censorship. I will present joint work with M. Mokdad where we construct a scattering theory for the massive and charged Dirac field in the interior region of a sub-extremal Kerr-Newman(-anti)-de Sitter black hole. In this work, we show existence, uniqueness, and asymptotic completeness of...
We study asymptotic quasi-normal mode expansions of linear fields propagating on a black hole background, in order to achieve this we exploit the compactified hyperboloidal approach in order to cast quasi-normal modes as eigenfunctions of a non-selfadjoint problem and we adopt a Keldysh scheme for the spectral construction of resonant expansions. The role of the scalar product structure in the...
Memory effects are persistent modifications of relatives observables (relative distance, relative velocity, etc ...) between test particles induced by the passage of a gravitational wave. These radiative effects stand as ones of the last predications of general relativity yet to be confirmed. On the one hand, modeling these memory effects is crucial for developing accurate waveform templates...
There are various proposals as to what initial state can give rise to an inflationary cosmology. The two most popular ones are the no boundary (Hartle-Hawking) and the tunneling (Vilenkin) proposals. Both of them explain only part of the observations and lead to some paradoxes. In this talk, I will review these proposals and I will propose a novel initial state (wavefunction) of the universe...
The study of perturbations around a black hole is crucial for the investigation of stability of the solution, as well as the modelization of gravitational waves emitted during the ringdown phase of a binary black hole merger. In general relativity, such perturbations are recast into two decoupled Schrödinger equations; in modified theories of gravity, this is often no longer possible due to...
I argue that translation-invariant dynamical systems on Lie groups are ubiquitous in Nature. Numerous examples are provided, ranging from basic mechanics and hydrodynamics to the edge modes of topological insulators and quantum gravity. The geometric approach to such setups yields observables that are natural but surprisingly overlooked in the literature, notably including Berry phases that...