  Numerical studies of black hole greybody factors indicate that Hawking
emission from a highly rotating black hole is strongly spin dependent, with
particles of highest spin (gravitons) dominating the energy spectrum. So far,
there has been no analytic explanation or description of this effect. Using
"gravitomagnetism", or the formal analogy between the Maxwell's field equations
for electro- magnetism and Einstein's equations for gravity, we were able to
establish a link between the spin of the rotating black hole and spin of an
emitted particle. Namely, the intrinsic spin of the particle creates a "mass
dipole moment" which interacts with external gravitomagnetic field whose source
is the rotation of the black hole. We showed that a rotating black hole prefers
to shed its spin, i.e. tends to emit particles with the spin parallel to its
own. We also showed that the probability for emission grows with the increasing
spin of the emitted particles. The amplification factors can be huge if a black
hole is highly rotating, i.e. close to extremal. When applied to central
galactic black holes, the same physical mechanism indicate that particles
orbiting around these black holes should have spins strongly correlated with
the spin of the black hole, which may have implications for cosmic rays
believed to be coming from these regions of space.
