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, and neutrinos. The spike luminosity depends on the halo density profile: halos with finite cores have unnoticeable spikes; halos with inner cusps may have spikes so bright that the absence of a neutrino signal from the galactic 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 matter.