Secular Resonance Sweeping in a Self–gravitating Planetesimal Disk, with Application to the Kuiper Belt

One of the more puzzling aspects of the Kuiper Belt is the high orbital inclinations exhibited by Kuiper Belt Objects (KBOs). This swarm of distant comets have apparent inclinations of ∼ 15◦ that to date have defied all simple explanations. Several distinct models have been offered as explanations for the Kuiper Belt’s dynamical excitation: gravitational stirring by protoplanets that may have once roamed the outer solar system [1], scattering of KBOs out into inclined Kuiper Belt orbits by the giant planets [2], inclination–pumping due to the close passage of another star [3], and sweeping the Kuiper Belt with secular resonances as the solar nebula gas dispersed [4]. Perhaps the most promising mechanism is secular resonance sweeping since this scenario can produce the very high orbital inclinations observed in the Kuiper Belt.