Low-energy electromagnetic radiation as an indirect probe of black-hole evaporation

We study the influence of black-hole evaporation on light propagation. The framework employed is based on the non-linear QED effective action at one-loop level. We show that the light-cone condition is modified for low-energy radiation due to black-hole evaporation. We discuss conditions under which the phase velocity of this low-energy radiation is greater than c . We also compute the modified light-deflection angle, which turns out to be significantly different from the standard GR value for black-hole masses in the range MPl≪M≲1019MPl.