Do Evaporating Black Holes Form Photospheres?

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Several authors, most notably Heckler, have claimed that the observable Hawking emission from a microscopic black hole is significantly modified by the formation of a photosphere around the black hole due to QED or QCD interactions between the emitted particles.

• In this paper we analyze these claims and identify a number of physical and geometrical effects which invalidate these scenarios.
• We point out two key problems.
• First, the interacting particles must be causally connected to interact, and this condition is satisfied by only a small fraction of the emitted particles close to the black hole.