Photon Ring Astrometry for Superradiant Clouds

Gravitational atoms produced from the superradiant extraction of rotational energy of spinning black holes can reach energy densities significantly higher than that of dark matter, turning black holes into powerful potential detectors for ultralight bosons. These structures are formed by coherently oscillating bosons, which induce oscillating metric perturbations deflecting photon geodesics passing through their interior. The deviation of nearby geodesics can be further amplified near critical bound photon orbits. We discuss the prospect of detecting this deflection using photon ring autocorrelations with the Event Horizon Telescope and its next-generation upgrade, which can probe a large unexplored region of the cloud mass parameter space when compared with previous constraints.

Automated summary

Gravitational atoms produced by the superradiant extraction of spinning black holes' rotational energy have higher energy densities than dark matter, making black holes potential detectors for ultralight bosons. These structures are formed by coherently oscillating bosons, which cause oscillations in the metric perturbations, deflecting the paths of photons passing through them. The deviation of nearby geodesics can be further amplified near critical bound photon orbits. We discuss the possibility of detecting this deflection using photon ring autocorrelations with the Event Horizon Telescope and its next-generation upgrade, which can explore a large unexplored region of the cloud mass parameter space compared to previous constraints.