Bremsstrahlung by static charges outside a static black hole ?
  We show that in complete analogy with the usual bremsstrahlung process, when studied from the coaccelerated observer's point of view, a charge moving along the integral curves of the static Killing field in the exterior of a static black hole gives rise to the emission of zero-energy photons, induced by the thermal bath of Hawking Radiation. 
G.E. Matsas, D. Sudarsky, and A. Higuchi