Supernova signals of light dark matter

TL;DR

This paper explores how supernova-produced light dark matter, especially in models with fermion dark matter and dark photons, can be detected via direct detection experiments, extending constraints and highlighting detection prospects.

Contribution

It extends supernova cooling constraints to strong coupling regimes and demonstrates the detectability of supernova-produced dark matter in current and future direct detection experiments.

Findings

Supernovae can produce copious light dark matter detectable on Earth.

Dark matter flux from supernovae can surpass galactic background in direct detection.

Detection potential spans many orders of magnitude in mass and coupling.

Abstract

Dark matter direct detection experiments have poor sensitivity to a galactic population of dark matter with mass below the GeV scale. However, such dark matter can be produced copiously in supernovae. Since this thermally-produced population is much hotter than the galactic dark matter, it can be observed with direct detection experiments. In this paper, we focus on a dark sector with fermion dark matter and a heavy dark photon as a specific example. We first extend existing supernova cooling constraints on this model to the regime of strong coupling where the dark matter becomes diffusively trapped in the supernova. Then, using the fact that even outside these cooling constraints the diffuse galactic flux of these dark sector particles can still be large, we show that this flux is detectable in direct detection experiments such as current and next-generation liquid xenon detectors. As a result, due to supernova production, light dark matter has the potential to be discovered over many orders of magnitude of mass and coupling.