We combine proper motion data from Gaia EDR3 and HST with line-of-sight velocity data to study the stellar kinematics of the ω Cen 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 ≲ 106 M⊙ within the ω Cen 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. While a compact core of stellar remnants may account for a dynamical mass up to ∼5 × 105 M⊙, they likely cannot explain the higher end of the range. This leaves open the possibility that this non-luminous dynamical mass component is comprised of non-baryonic dark matter. In comparison to the dark matter distributions around dwarf spheroidal galaxies, the ω Cen dark mass component is much more centrally concentrated. Interpreting the non-luminous mass distribution as particle dark matter, we use these results to obtain the J-factor, which sets the sensitivity to the annihilation cross-section. For the datasets considered, the range of median J-factors is ∼1022 − 1024 GeV2 cm−5, which is larger than that obtained for any dwarf spheroidal galaxy.

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We use Fermi-LAT data to analyze the faint gamma-ray source located at the center of the Sagittarius (Sgr) dwarf spheroidal galaxy. In the 4FGL-DR3 catalog, this source is associated with the globular cluster, M54. We investigate the spectral energy distribution and spatial extension of this source, with the goal of testing two hypotheses: (1) the emission is due to millisecond pulsars within M54, or (2) the emission is due to annihilating dark matter from the Sgr halo. For the pulsar interpretation, we consider a two-component model which describes both the lower-energy magnetospheric emission and possible high-energy emission arising from inverse Compton scattering. We find that this source has a point-like morphology at low energies, consistent with magnetospheric emission, and find no evidence for a higher-energy component. For the dark matter interpretation, we find the signal favors a dark matter mass of mχ = 29.6 ± 5.8 GeV and an annihilation cross section of σv = (2.1 ± 0.59) × 10−26 cm3 s−1 for the $b \bar{b}$ channel (or mχ = 8.3 ± 3.8 GeV and σv = (0.90 ± 0.25) × 10−26 cm3 s−1 for the τ+τ− channel), when adopting a J-factor of J = 1019.6 GeV2 cm−5. This parameter space is consistent with gamma-ray constraints from other dwarf galaxies and with dark matter interpretations of the Galactic Center Gamma-Ray Excess.