Primordial black holes from spectator field bubbles

We study the evolution of light spectator fields in an asymmetric polynomial potential. During inflation, stochastic fluctuations displace the spectator field from the global minimum of its potential, populating the false vacuum state and thereby allowing for the formation of false vacuum bubbles. By using a lattice simulation, we show that these bubbles begin to contract once they re-enter the horizon and, if sufficiently large, collapse into black holes. This process generally results in the formation of primordial black holes, which, due to the specific shape of their mass function, are constrained to yield at most 1% of the total dark matter abundance. However, the resulting population can source gravitational wave signals observable at the LIGO-Virgo experiments, provide seeds for supermassive black holes or cause a transient matter-dominated phase in the early Universe.

Automated summary

The study investigates the evolution of light spectator fields in an asymmetric polynomial potential. It shows that during inflation, these fields can form false vacuum bubbles, which collapse into black holes once they re-enter the horizon. The resulting population of primordial black holes is constrained to contribute at most 1% of the total dark matter abundance, but they can provide observable gravitational wave signals, act as seeds for supermassive black holes, or cause a transient matter-dominated phase in the early Universe.