Nonlinear fate of spatially distinct neighboring curvature peaks

Determine whether spatially distinct neighboring primordial curvature peaks collapse collectively, remain dynamically independent and form multiple primordial black holes, or fail to collapse in a radiation-dominated Universe.

Background

The paper studies primordial black-hole formation beyond the usual isolated, approximately spherical high-peak approximation. Neighboring curvature perturbations can be correlated and embedded in a nontrivial spatial environment, so their nonlinear evolution may not map each primordial peak to a separate black hole.

Previous spherical studies of concentric fluctuations demonstrated that surrounding structure can modify the collapse threshold, but spherical symmetry forces all fluctuations to share a common center and therefore cannot produce genuine primordial-black-hole multiplicity. The unresolved problem is to determine the nonlinear outcome when the peaks are spatially separated: collective collapse into one black hole, independent collapse into multiple black holes, or dispersal without black-hole formation.