Comment on “Kerr Black Holes as Particle Accelerators to Arbitrarily High Energy”

A Comment on the Letter by Máximo Bañados, Joseph Silk, and Stephen M. West [Phys. Rev. Lett. 103, 111102 (2009)].

Figure 1

Energy spectrum for $l=m=2$ and different values of $L/L_{\mathrm{scat}}$ (as indicated in the legend). Inset: for small $\delta$, a fit of the numerics yields ${\mu }^{-2}M{E}_{\mathrm{tot}}\sim -0.11-0.18\log \delta$.