Orateur
Description
In this talk, based on arXiv:2402.00600, we revisit the initial spatial
clustering of Primordial Black Holes (PBHs) originating from the Hubble
reentry of large Gaussian density fluctuations in the early Universe.
Using an excursion-set approach, we derive the two-point correlation
functions of PBHs, properly accounting for the “cloud-in-cloud”
mechanism. Our expressions naturally and intrinsically correlate the
formation of pairs of PBHs, which is a key difference with the Poisson
model of clustering. Our approach effectively includes short-range
exclusion effects and clarifies the clustering behaviors at small scale:
PBHs are anticorrelated at short distances. Using a scale-independent
collapse threshold, we derive explicit expressions for the excess
probability to find pairs of PBHs, as well as the excess probability to
find pairs with asymmetric mass ratio. Our framework is model
independent by construction, and we discuss possible other applications.
