The detailed calculations are possible due to an effective field theory formulation of quantum gravity in the long wavelength, low spacetime curvature limit.
Quantum Hair During Gravitational Collapse
X. Calmet, R. Casadio, S. Hsu, F. Kuipers
We consider quantum gravitational corrections to the Oppenheimer-Snyder metric describing time-dependent dust ball collapse. The interior metric also describes Friedmann-Lemaitre-Robertson-Walker cosmology and our results are interpreted in that context. The exterior corrections are an example of quantum hair, and are shown to persist throughout the collapse. Our results show the quantum hair survives throughout the horizon formation and that the internal state of the resulting black hole is accessible to outside observers.