Primordial black holes from stochastic inflation - David Wands
When: Friday, October 23, 2026, 3:00 PM - 4:00 PM
Where: G. O. Jones, Room 610, Mile End
Speaker: David Wands (ICG, Portsmouth)
Title: Primordial black holes from stochastic inflation
Abstract:
The idea that primordial black holes could form from large density perturbations in the early radiation-dominated universe has intrigued cosmologists since the idea was proposed by Carr and Hawking in the 1970s. They could in principle have a wide range of masses with a wide range of astrophysical effects, and there has been a resurgence of interest in the era of gravitational wave astronomy with the idea that we might be able to directly detect primordial black holes through their gravitational radiation produced either when they form or in binary mergers. Primordial density perturbations, as observed for example in the cosmic microwave background radiation, are thought to originate from microscopic quantum fluctuations during inflation, a period of accelerated expansion in the very early universe before the radiation-dominated era. Inflation generates primordial density perturbations on all cosmic scales, but until recently it has mainly been studied in the context of semi-classical, slow-roll inflation leading to small almost scale-invariant, almost Gaussian density perturbations on the largest observable scales. I will discuss recent work exploring large, nonlinear, fluctuations during inflation which could provide the seeds for the formation of primordial black holes. In particular I will present results from a stochastic description of inflation used to model the non-Gaussian distribution of rare, but large primordial perturbations and some of the challenges going beyond the semi-classical, slow-roll regime.