Dark matter annihilation at the galactic center

Cold dark matter near the galactic center is accreted by the central black hole into a dense spike. Particle dark matter annihilation makes the spike a compact source of photons, electrons, positrons, protons, antiprotons., a nd neutrinos. The spike luminosity depends on the halo density profile: hal os with finite cores have unnoticeable spikes; halos with inner cusps may h ave spikes so bright that the absence of a neutrino signal from the galacti c center already places upper limits on the density slope of the inner halo . Future neutrino telescopes observing the galactic center could probe the inner structure of the dark halo or indirectly find the nature of dark matt er.