  The observation of a possible electromagnetic counterpart by the Fermi GBM
group to the aLIGO detection of the merger of a black hole binary has spawned a
number of ideas about its source. Furthermore, observations of fast radio
bursts (FRBs) have similarly resulted in a range of new models that might endow
black hole binaries with electromagnetic signatures. In this context, even the
unlikely idea that astrophysical black holes may have significant charge is
worth exploring, and here we present results from the simulation of weakly
charged black holes as they orbit and merge. Our simulations suggest that a
black hole binary with mass comparable to that observed in GW150914 could
produce the level of electromagnetic luminosity observed by Fermi GBM
($10^{49}$ ergs/s) with a non-dimensional charge of $q \equiv Q/M = 10^{-4}$
assuming good radiative efficiency. However even a charge such as this is
difficult to imagine avoiding neutralization long enough for the binary to
produce its electromagnetic counterpart, and so this value would likely serve
simply as an upper bound. On the other hand, one can equivalently consider the
black holes as having acquired a magnetic monopole charge that would be easy to
maintain and would generate an identical electromagnetic signature as the
electric charges. The observation of such a binary would have significant
cosmological implications, not the least of which would be an explanation for
the quantization of charge itself. We also study such a magnetically charged
binary in the force-free regime and find it much more radiative, reducing even
further the requirements to produce the counterpart.
