Primordial Black Holes: From formation to explosion

by Joaquim Iguaz (U Mass Amherst)

Thursday 5 Jun 2025, 12:00 → 13:00 Europe/Madrid

IFAE Seminar Room (In-Person)

Since the first detection of gravitational waves ten years ago, interest in Primordial Black Holes (PBHs) has grown significantly—despite the concept dating back to the 1960s. The standard formation mechanism involves the collapse of large overdensities reentering the horizon in the early universe, but it requires substantial fine-tuning, motivating the exploration of alternative scenarios. One intriguing possibility arises during preheating, through the self-resonant growth of inflaton fluctuations. However, we find that PBH formation is not a generic outcome. Instead, we observe the formation of metastable oscillons, which may themselves have interesting implications. I will also discuss the exciting prospect of observing an exploding PBH in the near future, an unprecedented event that could offer definitive insights into the particle content of the universe. In particular, we explore a scenario involving a new dark sector that can generate quasi-extremal PBHs, leading to large burst rates consistent with all existing constraints on PBH abundance.

The talk is based on arXiv:2406.09122 and arXiv:2503.10755.