Indirect dark matter searches at ultrahigh energy neutrino detectors

Understand

High to ultrahigh energy neutrino detectors can uniquely probe the properties of dark matter $\chi$ by searching for the secondary products produced through annihilation and/or decay processes.

• We evaluate the sensitivities to dark matter thermally averaged annihilation cross section $\langle\sigma v\rangle$ and partial decay width into neutrinos $\Gamma_{\chi\rightarrow\nu\bar{\nu}}$ (in the mass scale $10^7 \leq m_\chi/{\rm GeV} \leq 10^{15}$) for next generation observatories like POEMMA and GRAND.
• We show that in the range $ 10^7 \leq m_\chi/{\rm GeV} \leq 10^{11}$, space-based Cherenkov detectors like POEMMA have the advantage of full-sky coverage and rapid slewing, enabling an optimized dark matter observation strategy focusing on the Galactic center.
• We also show that ground-based radio detectors such as GRAND can achieve high sensitivities and high duty cycles in radio quiet areas.