Constraints on Dark Matter Structures around Gaia Black Holes

We demonstrate that Gaia’s detection of stars on wide orbits around black holes opens a new observational window on dark matter structures – such as scalar clouds and dark matter spikes – predicted in a range of theoretical scenarios. Using precise radial velocity measurements of these systems, we derive state-of-the-art constraints on dark matter density profiles and particle masses in previously unexplored regions of parameter space. We also test the black hole hypothesis against the alternative of a boson star composed of light scalar fields.