Influence of a Distant Planet on the Detached Kuiper Belt Inclination Distribution

A massive planet in the distant solar system has been previously proposed to explain some curious features seen in the current population of observed Trans-Neptunian objects (TNOs). We use N-body simulations of the outer solar system to model the effects of a distant massive planet on the formation and distribution of the Kuiper Belt. The additional 9th planet can cause TNOs to populate regions of orbital space that would not be populated without the influence of the 9^th planet. For instance in an 8-planet model, Kozai-Lidov oscillations are the main mechanism to populate the distant, detached region. This causes the low inclination space to remain unpopulated, as the out-of-phase oscillations of inclination and eccentricity within Kozai-Lidov cycles force the TNOs’ inclinations to be high as their perihelia increase (and eccentricities decrease). However, with the additional secular interactions from the 9^th planet, the low inclination region of distant, detached TNOs is also populated in our 9-planet simulations. This disparity in the relative numbers of high and low inclination bodies could provide a useful new constraint on a possible 9^th planet in the distant solar system. Further detections of distant, detached TNOs which should be observed in the coming years, could help us better understand the dynamics of the outer solar system.