Quantum gravitational collapse and Hawking radiation in $2+1$ dimensions

We develop the canonical theory of gravitational collapse in $2+1$ dimensions with a negative cosmological constant and obtain exact solutions of the Wheeler-DeWitt equation regularized on a lattice. We employ these solutions to derive the Hawking radiation from black holes formed in all models of dust collapse. We obtain an (approximate) Planck spectrum near the horizon characterized by the Hawking temperature $T_{\mathrm{H}}=\hslash \sqrt{G\Lambda M}/2\pi$, where $M$ is the mass of a black hole that is presumed to form at the center of the collapsing matter cloud and $-\Lambda$ is the cosmological constant. Our solutions to the Wheeler-DeWitt equation are exact, so we are able to reliably compute the gray-body factors that result from going beyond the near-horizon region.