Vacuum polarization throughout general subtracted black hole spacetimes
  We compute the vacuum polarization of a massless minimally co pled scalar field in a background given by a black hole with subtracted geometry. Extending previous results for the horizon of rotating black holes with no charge, we obtain an analytical expression for the vacuum polarization that is valid throughout the spacetime and for arbitrary rotation and charge parameters. The vacuum polarization diverges at the inner horizon and the quantum state cannot be extended to the inside of it. 
Alejandro Satz and Mirjam Cvetic
gr-qc hep-th