Collective gravity in the Outer Solar System

Eccentric trans-Neptunian objects are unstable to out-of-plane buckling via collective gravitational torques. This instability grows orbital inclinations, raises perihelia, and clusters arguments of perihelion. Here we show how the inclusion of giant planets affects the dynamics by raising the minimum mass of the population needed to undergo the instability, and producing a perihelion gap at hundreds of AU. Finally we look at the long-term evolution of the system and find apsidal alignment of orbits.