Oscillon and Black Hole Formation in Cosmological Preheating
Following cosmic inflation, the non-perturbative and highly non-linear dynamics of preheating can possibly form dense oscillons and might seed primordial black holes. Numerical relativity (NR) is required to study these non-linear dynamics. In this talk, I will briefly introduce NR and its applications in the early universe, in particular the preheating phase. I will first discuss single-field preheating in general relativity (GR), followed by our recent work studying the effect of higher-derivative corrections on preheating in Einstein-scalar-Gauss-Bonnet gravity. I will close with multifield kinetic preheating, where black holes form, and show preliminary results in which we follow the black hole formation and its subsequent dynamics.