  It is well established that black holes reside in the central regions of
virtually all types of known galaxies. Recent observational and numerical
studies however challenge this picture, suggesting that intermediate-mass black
holes in dwarf galaxies may be found on orbits far from the center. In
particular, constant-density cores minimize orbital energy losses due to
dynamical friction, and allow black holes to settle on stable off-center
orbits. Using controlled simulations, we study the dynamics of off-center black
holes in dwarf galaxies with such cores. We propose a new scenario to describe
off-center mergers of massive black holes, starting with a Jacobi capture. We
focus on initially circular and co-planar black hole orbits and explore a large
parameter space of black hole masses and orbital parameters. We find that
Jacobi captures are a complex and chaotic phenomenon that occurs in about 13%
of cases in this simplified setup, and we quantify how the likelihood of
capture depends on the simulation parameters. We note that this percentage is
likely an upper limit of the general case. Nevertheless, we show that Jacobi
captures in cored dwarf galaxies can facilitate the formation of off-center
black hole binaries, and that this process is sufficiently common to have a
substantial effect on black hole growth. While our setup only allows for
temporary captures, we expect dissipative forces from baryons and
post-Newtonian corrections to maintain the captures over time and to lead to
the formation of stable binary systems. This motivates future studies of the
effectiveness of such dissipative forces, within stripped nuclei or globular
clusters, in forming stable bound systems.
