Dark and luminous mass components of Omega Centauri with stellar kinematics

Understand

We combine proper motion data from $Gaia$ EDR3 and HST with line-of-sight velocity data to study the stellar kinematics of the Omega Centauri globular cluster.

• Using a steady-state, axisymmetric dynamical model, we measure the distribution of both the dark and luminous mass components.
• Assuming both Gaussian and NFW mass profiles, depending on the dataset, we measure an integrated mass of $\lesssim 10^6$ M$_\odot$ within the Omega Centauri half-light radius for a dark component that is distinct from the luminous stellar component.
• For the HST and radial velocity data, models with a non-luminous mass component are strongly statistically preferred relative to a stellar mass-only model with a constant mass-to-light ratio.