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Can the Kuiper Belt’s 3:2 orbital distribution result from stability sculpting?

Presentation #501.02 in the session “KBOs and Multiples”.

Published onJun 01, 2021
Can the Kuiper Belt’s 3:2 orbital distribution result from stability sculpting?

The population of Kuiper belt objects (KBOs) in mean-motion resonances with Neptune serves as a signpost for the dynamical evolution of the Solar System. We use the N-body code Rebound to simulate the evolution of the 3:2 mean-motion resonant population after a presumed gravitational upheaval. KBOs in the simulation are given random initial orbital parameters, with eccentricities and pericenters drawn from ranges that span the initial stable extent of the resonance, and then allowed to orbit over a 4.5 billion-year timescale in the presence of the four giant planets. Through a process we call “stability sculpting”, non-resonant particles are scattered over time while the remaining resonant objects define a long-term-stable area of phase space. These models are then forward-biased using the Outer Solar System Origins Survey (OSSOS) Survey Simulator before being statistically compared against the OSSOS observational sample. Consistent with previous results, we find that stability sculpting only modestly changes the inclination distribution. Furthermore, initial pericenter ranges extending all the way to the location of the resonance overproduce low-eccentricity objects. With an initial inclination distribution similar to that currently observed and a restricted initial pericenter range, our model is able to produce non-rejectable distributions for semi-major axis (a), eccentricity (e), and resonant argument (phi) when compared to OSSOS data. Our models are consistent with a broken power law size distribution for the 3:2 population. However our model produces a Kozai fraction lower than the observed fraction despite occupying the same area in phase space. We thus conclude that gravitational upheaval followed by stability sculpting can produce the majority of the currently-observed 3:2 population. The observed Kozai population may require an alternative dynamical emplacement model.

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