Possible High-Energy Neutrino Emission from Dark Matter Annihilation in the Disrupting Dwarf Galaxy Boötes~III

Abstract

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 Boötes~III, the core of the Styx stream, with the DM mass of $m_{\chi }\simeq 10$--$31\mathrm{TeV}$. 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 $J_{\mathrm{ann}}$, ${\log }_{10}(J_{\mathrm{ann}}/\mathrm{Ge}{\mathrm{V}}^2\mathrm{c}{\mathrm{m}}^{-5})\gtrsim 19.1_{-0.5}^{+0.3}$. This limit is broadly consistent with empirical estimates of $J_{\mathrm{ann}}$ for Boötes~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.

7 pages, 6 figures, accepted for publication in Physical Review D