Paper detail

Constraining Ultra Light Dark Matter with the Galactic Nuclear Star Cluster

We use the Milky Way&#39;s nuclear star cluster (NSC) to test the existence of a dark matter &#39;soliton core&#39;, as predicted in ultra-light dark matter (ULDM) models. Since the soliton core size is proportional to mDM^{-1}, while the core density grows as mDM^{2}, the NSC (dominant stellar component within about 3 pc) is sensitive to a specific window in the dark matter particle mass, mDM. We apply a spherical isotropic Jeans model to fit the NSC line-of-sight velocity dispersion data, assuming priors on the precisely measured Milky Way&#39;s supermassive black hole (SMBH) mass and the well-measured NSC density profile. We find that the current observational data reject the existence of a soliton core for a single ULDM particle with mass in the range 10^{-20.4} < mDM < 10^{-18.5} eV, assuming that the soliton core structure is not affected by the Milky Way&#39;s SMBH. We test our methodology on mock data, confirming that we are sensitive to the same range in ULDM mass as for the real data. Dynamical modelling of a larger region of the Galactic centre, including the nuclear stellar disc, promises tighter constraints over a broader range of mDM. We will consider this in future work.