Disruptions of stars and binary systems on chaotic orbits in an axisymmetric Milky Way centre

Non-spherical potentials allow a wide range of trajectories, both regular and chaotic, whose periapse distances can vary orbit to orbit. In particular, chaotic trajectories can bring a system arbitrarily close to the central massive black hole leading to a disruption. In this paper, we work with an observationally benchmarked model of the innermost 200 pc of the Milky Way and show that low z-angular momentum trajectories are commonly chaotic. We compute the time-scales and properties of close pericentre passages, and compare the implied collisionless disruption rate to the well-studied collisional rate from two-body scatterings. We find that the relative collisionless rate can dominate by orders of magnitude. Our calculations are relevant for a wide range of disruption phenomena, including the production of hypervelocity stars and tidal disruption events. Most of these disruptions involve stars that come from the nuclear stellar cluster, with a pericentre distribution that strongly favours shallow encounters, and a preference for high inclination interactions. The latter implies that unbound disrupted material - whether ejected stars or stellar debris - would be preferentially directed towards the Galactic poles. Many of our conclusions apply generally to any galaxy with a non-spherical galactic centre potential and central massive black hole.