Photon Orbital Angular Momentum and Proca effects in rotating and   charged spacetimes
  We analyze the effect of Proca mass and orbital angular momentum of photons imposed by a structured plasma in Kerr-Newman and Reissner-Nordstrom-de Sitter spacetimes. The presence of characteristic lengths in a turbulent plasma converts the virtual Proca photon mass on orbital angular momentum, with the result of decreasing the virtual photon mass. The combination of this plasma effect and that of the gravitational field leads to a new astrophysical phenomenon that imprints a specific distribution of orbital angular momentum into different frequencies of the light emitted from the neighborhood of such a black hole. The determination of the orbital angular momentum spectrum of the radiation in different frequency bands leads to a complete characterization of the electrostatic and gravitational field of the black hole and of the plasma turbulence, with fundamental astrophysical and cosmological implications. 
F. Tamburini (1) and B.Thid\'E (2) ((1) Department of Astronomy,   University of Padova, vicolo dell' Osservatorio 3, Padova...
gr-qc astro-ph.HE quant-ph