New Multi-messenger Probe of Dark Matter-Nucleon Interactions from Ultra-high Energy Cosmic Ray Acceleration

Abstract: It has been suggested that the density of dark matter (DM) halo can be highly enhanced around supermassive black holes at the centers of massive galaxies. If real, these DM \emph{spikes} would offer new opportunities to probe the properties of DM. In this work, we point out that DM spikes can significantly impact the composition and survivability of ultra-high-energy cosmic rays accelerated near supermassive black holes. A large DM-nucleon cross section would fragment heavy nuclei into lighter elements and prevent them from attaining the energies observed at Earth. While the origin of cosmic rays remains a mystery, we show that if the highest-energy cosmic rays on Earth come from sources like NGC1068, then cross sections of size $$σ<em>{χp} \leq 3 \times 10^{-34} \left( \frac{m</em>χ}{\mathrm{GeV}}\right)\;\mathrm{cm<sup>{2}}$$ would be excluded by cosmic ray data. These bounds can be competitive with other existing probes in the DM mass region $m_χ\in [5\;\mathrm{MeV}, 50\;\mathrm{MeV}]$. While the uncertainties on the acceleration mechanism of cosmic rays prevent us from setting robust limits, our study highlights an important connection between DM spikes and cosmic ray physics that is complementary to existing cosmological and direct detection constraints.