A black hole window into p-wave dark matter annihilation

Understand

We present a new method to measure or constrain p-wave-suppressed cross sections for dark matter (DM) annihilations inside the steep density spikes induced by supermassive black holes.

• We demonstrate that the high DM densities, together with the increased velocity dispersion, within such spikes combine to make thermal p-wave annihilation cross-sections potentially visible in gamma-ray observations of the Galactic center (GC).
• The resulting DM signal is a bright central point source with emission originating from DM annihilations in the absence of a detectable spatially-extended signal from the halo.
• We define two simple reference theories of DM with a thermal p-wave annihilation cross-section and establish new limits on the combined particle and astrophysical parameter space of these models, demonstrating that Fermi is currently sensitive to thermal p-wave DM over a wide range of possible scenarios for the DM distribution in the GC.