Dynamical constraints on a dark matter density spike at the Galactic Centre from stellar orbits
In this work, we use current astrometric and spectroscopic data on the S2 star at the Galactic Centre to derive specific constraints on the size of a dark matter density spike around the central supermassive black hole Sgr A*. Our limits are the best direct constraints on a DM spike at the GC for non-annihilating dark matter and exclude a spike with radius greater than a few pc for cuspy outer halos and a few hundred pc for cored outer halos.