Dynamical constraints on a dark matter spike at the Galactic Centre from stellar orbits

TL;DR

This study uses stellar orbit data to place the most stringent direct constraints on the size of a dark matter spike around the Galactic Centre's supermassive black hole, limiting its radius based on the nature of the dark matter halo.

Contribution

It provides the first direct observational constraints on the size of a dark matter spike at the Galactic Centre for non-annihilating dark matter.

Findings

Excludes dark matter spikes larger than a few tens of parsecs for cuspy halos.

Rules out spikes larger than a few hundred parsecs for cored halos.

Sets the most stringent direct limits to date on dark matter spike size at the Galactic Centre.

Abstract

In this work I use astrometric and spectroscopic data on the S2 star at the Galactic Centre (GC) up to 2016 to derive specific constraints on the size of a dark matter (DM) spike around the central supermassive black hole Sgr A*. These limits are the best direct constraints on a DM spike at the GC for non-annihilating DM and exclude a spike with radius greater than a few tens of parsecs for cuspy outer halos and a few hundred parsecs for cored outer halos.