Possible High-Energy Neutrino Emission from Dark Matter Annihilation in the Disrupting Dwarf Galaxy Bo\"{o}tes~III

We report the first search for high-energy neutrino emissions from dark matter (DM) annihilation in stellar-stream cores. Motivated by a recent gamma-ray study that proposed these cores as a new class of indirect DM targets, we analyze three stream cores in the Northern Hemisphere using the public ten-year track-like neutrino data released by IceCube. Under the $\chi\chi\to\nu\bar{\nu}$ annihilation hypothesis, the most significant excess among the three targets is found at the position of the nearby dwarf galaxy Bo\"{o}tes~III, the core of the Styx stream, with a best-fit DM mass of 26.5\,TeV. The excess has a post-trial significance of $3.1\sigma$. Considering the existing IceCube dwarf-galaxy limit for the same channel, we obtain a limit on the J-factor $J_{\rm ann}$, $\log_{10}(J_{\rm ann}/{\rm GeV^2\,cm^{-5}})\gtrsim 19.1^{+0.3}_{-0.5}$. This limit is broadly consistent with empirical estimates of $J_{\rm ann}$ for Bo\"{o}tes~III. The results provide the first candidate target with a possible HE neutrino signal associated with DM annihilation. This neutrino excess and the general existence of DM-induced neutrino signals from other similar sources will be confirmed with the near-future large high-energy neutrino detectors, thus enabling us to probe the nature of DM particles.