Topologically induced black hole charge and its astrophysical
  manifestations
  Quantum corrected effective action for gravity contains massive spin-2 ghost
degrees of freedom and admits a topological term which couples longitudinal
vector degrees of freedom of the massive spin-2 to Maxwell's electromagnetism.
We argue that in the presence of otherwise unobservable gravimagnetic poles
this topological term induces an electric charge on a black hole which can be
probed through the associated electric and magnetic fields. In particular, we
discuss the electromagnetic follow up from the LIGO-sensitive charged black
hole binary coalescence due to the synchrotron radiation from the surrounding
plasma and the shadow of super-massive charged black holes.
