NEHOP'25 - New Horizons in Primordial Black Hole Physics

Inflationary and Gravitational Wave Signatures of Small Primordial Black Holes as Dark Matter

21 May 2025, 16:50

20m

Brussels

PBHs and GWs

Speaker

Benjamin Gladwyn (University of Oxford (GB))

Description

Mounting evidence suggests that the semi-classical description of a black hole breaks down at the latest after losing an~$O(1)$ fraction of its mass. As a result, effects such as memory burden can slow down evaporation so that small primordial black holes (PBHs), in particular those in the mass range~${10}^6\text{g}$ to~${10}^9\text{g}$, become viable dark matter candidates. I will present our investigation into the production of PBHs from a prototype model of polynomial inflation with a non-minimal coupling to gravity and demonstrate that a sufficiently small PBH mass alleviates any tension with CMB observations. Furthermore, I will present bounds on the scalar-induced stochastic gravitational wave (GW) background generated by small PBH formation. Whilst we identify some prospects for observation with future GW detectors, I will highlight the need to develop new experiments for high-frequency GW detection in the $\sim \text{kHz}$ to $\sim \text{MHz}$ range.

Based on:
Inflationary and Gravitational Wave Signatures of Small Primordial Black Holes as Dark Matter. W. Barker, B. Gladwyn and S. Zell, https://arxiv.org/abs/2410.11948, accepted for publication in Phys. Rev. D