Orateur
Description
Understanding how the presence of primordial black holes (PBH) affects the cosmic history is a crucial endeavor for the refine our cosmological models. When studying PBHs, a key difficulty is that the notion drawn from the study of asymptotically flat and stationary black holes, such as the Schwarzschild and Kerr black hole solutions, are no longer available. PBH are by definition asymptotically FLRW and fully dynamical. Therefore, a characterization of their properties requires new tools to compute their quasi-local mass, characterize their dynamical horizons and define their temperature. Additionally, a central question is how to provide a gauge-invariant characterization for an inhomogeneity embedded in a cosmological spacetime to form a black hole. The current criteria based on the compaction function and the Misner-Sharp mass has revealed very useful but is limited to spherically symmetric collapse. In this talk, I will present two new results allowing to characterize asymptotically FRW black holes and thus PBH. First I will introduce a new notion of quasi-local mass adapted to asymptotically FLRW geometries which hold beyond spherical symmetry. Then I will discuss how this can be used to provide an improved notion of compaction function for PBHs beyond spherical symmetry. Finally, I will present new exact analytical solutions of General Relativity describing asymptotically flat axisymmetric black holes solutions embedded in cosmology and discuss how they can be understood as exact model of PBHs. They will serve to confront and test the new definitions introduced in this talk.
