This is a very "dense" paper. So: if dark matter is something that annihilates itself, that's a two-particle interaction, so its macroscopic rate scales as density squared ρ². If there's a black hole in the solar system, the dark matter halo immediately surrounding it would be compressed far denser than around a normal object, so it'd have a much brighter annihilation signal. Nothing's known about dark matter annihilation. They speculate, if its cross section is large enough, this annihilation could be observable by gamma-ray telescopes like Fermi or the upcoming CTA. And that would distinguish a black hole from something else. That's all I could understand. It'd be a discovery of a solar system black hole, and new dark matter physics, two-for-one.
I'm curious what math led to that funny exponent in eq.(5): ρ(r) ~ r^{-9/4}.
I'm curious what math led to that funny exponent in eq.(5): ρ(r) ~ r^{-9/4}.