Towards an understanding of the threshold of collapse in full generality

Abstract:
We study dynamical solutions to the Einstein field equations (EFEs) in the strong field regime of gravity, making use of real or complex scalar field matter which may induce gravitational collapse into black holes (BHs). In that regime, the nonlinearities of general relativity (GR) cannot be neglected and, thus, we employ numerical relativity (NR) simulations with the aim to address various fundamental questions. In fact, black hole formation serves as an ideal laboratory in order to test the limits of the theory of general relativity and of our understanding of singularities.

On one hand, by constructing a thought experiment, the dynamical formation of astrophysical size black holes can facilitate the study of a potential breakdown of the classical theory that may be associated to the creation of a singularity. On the other hand, critical phenomena in gravitational collapse at the threshold between BH formation or dispersion probe naked singularities, test the validity of the weak cosmic censorship conjecture and, consequently, push the boundaries of our comprehension of GR under extreme spacetime conditions. Our ultimate objective is to comprehend the phenomena at the verge of collapse for diverse matter models, devoid of any symmetry assumptions.

Nevertheless, there are several intermediate stages that we must traverse to gradually progress towards our ultimate goal. In this presentation, I will focus on two primary projects involving gravitational collapse that represent a direct outcome of my Ph.D. research over the past two years.

The first project explores the formation of astrophysical black holes through real scalar field collapse, while the second project delves into the investigation of the threshold of collapse of a complex scalar field in axisymmetry. In the forthcoming discussion, we will explore the key findings, implications, and future directions emerging from these projects, providing valuable insights into the active field of research of the threshold of gravitational collapse and its consequences for our understanding of singularities in GR.