Limits on dark matter annihilation in prompt cusps from the isotropic gamma-ray background

TL;DR

This paper uses 14 years of Fermi-LAT gamma-ray data to place new constraints on dark matter annihilation in early-universe cusps, significantly limiting certain dark matter models below 120 GeV.

Contribution

It provides the first strong observational constraints on dark matter annihilation in prompt cusps using isotropic gamma-ray background data.

Findings

Excluded dark matter annihilation to b-bbar for masses below 120 GeV at 95% confidence

Demonstrated that early-universe cusps contribute significantly to gamma-ray flux

Set new limits on dark matter annihilation cross sections

Abstract

Recent studies indicate that thermally produced dark matter will form highly concentrated, low-mass cusps in the early universe that often survive until the present. While these cusps contain a small fraction of the dark matter, their high density significantly increases the expected gamma-ray flux from dark matter annihilation, particularly in searches of large angular regions. We utilize 14 years of Fermi-LAT data to set strong constraints on dark matter annihilation through a detailed study of the isotropic gamma-ray background, excluding with 95% confidence dark matter annihilation to $b\bar{b}$ final states for dark matter masses below 120 GeV.