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.
Highlights
The particle nature of dark matter (DM) remains one of the largest outstanding puzzles in physics
Even in parameter space outside the cooling bound, a supernova can still produce a vast flux of light dark matter particles
Using a Monte Carlo Boltzmann particle transport simulation, we are able to compute the DM flux in the trapped regime, which allows us to estimate the reach of direct detection experiments that were originally expected to only have sensitivity to dark matter with masses above ∼GeV
Summary
The particle nature of dark matter (DM) remains one of the largest outstanding puzzles in physics. A large ongoing experimental effort is searching for dark matter candidates with masses in the GeV–TeV range (weakly-interacting massive particles, or “WIMPs”), largely motivated by the WIMP miracle (see, e.g., [2]) These experiments have achieved incredible sensitivity to dark matter by searching for very small energy depositions from dark matter scattering with nuclei in extremely clean environments. Core-collapse supernovae (SN) can reach core temperatures in excess of 30 MeV for Oð10Þ seconds, allowing them to produce vast thermal fluxes of particles with masses ≲Oð100Þ MeV at relativistic speeds This makes them an ideal astrophysical source for sub-GeV dark matter. For examples of existing cooling constraints on pair-produced particles, see, e.g., Refs. [13,14,15,16,17,18,19,20,21]
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