Description
In the first part of this talk I will present results from numerical relativity simulations of a toy-model cosmic web of over-densities, voids and filaments with the Einstein Toolkit, evolving from standard growing-mode perturbative CDM initial conditions in the matter era, at z ~ 300. I will show how the first collapse of peaks of over-densities is very well predicted by the simple "top hat” model (AKA Oppenheimer-Sneyer collapse). Although this simple cosmic web structure doesn’t assume any symmetries, the collapse of peaks is quasi-spherical, which naturally leads to the conjecture that a horizon can form very early. In the second part I will briefly present current numerical relativity efforts to identify a horizon enclosing these CDM peaks, as well as analytic results from Galoppo, Bruni and Harada 2605.30145 (based on exact solutions of Einstein equations) showing that supermassive black hole seeds can form from the direct collapse of the peaks of overdensities in the CDM distribution, with masses M ~ 10^3-10^6 at z ~ 10, or even earlier.