After being destroyed by a binary supermassive black hole, a stellar density
cusp can regrow at the center of a galaxy via energy exchange between stars
moving in the gravitational field of the single, coalesced hole. We
illustrate this process via high-accuracy N-body simulations.
Regeneration requires roughly one relaxation time and the new cusp
extends to a distance of roughly one-fifth the black hole's influence
radius, with density rho ~ r-7/4; the mass in the cusp
is of order
10% the mass of the black hole. Growth of the cusp is preceded by a
stage in which the stellar velocity dispersion evolves toward isotropy
and away from the tangentially-anisotropic state induced by the
binary. We show that density profiles similar to those observed at
the center of the Milky Way and M32 can regenerate themselves in several
Gyr following infall of a second black hole; the presence of a density
cusp at the centers of these galaxies can therefore not be used to infer
that no merger has occurred. We argue that Bahcall-Wolf cusps are
ubiquitous in stellar spheroids fainter than M(V) ~ -18.5 that
contain supermassive black holes, but the cusps have not been
detected outside of the Local Group since their angular sizes are
less than 0.1 arc seconds. We show that the presence of a cusp implies a
lower limit of ~10-4 per year on the rate of stellar tidal
disruptions, and discuss the consequences of the cusps for gravitational
lensing and the distribution of dark matter on sub-parsec scales.