Numerical estimation of the capture ability of Neptunian mean motion resonances

TL;DR

This paper quantitatively analyzes how Neptune's outward migration influences the capture of trans-Neptunian objects into mean motion resonances, providing empirical formulas for capture efficiency and eccentricity thresholds.

Contribution

It introduces a systematic numerical framework and empirical expressions for resonance capture efficiency during Neptune's migration, advancing understanding of Solar System evolution.

Findings

Capture efficiency depends on eccentricity, resonance order, and distance, but is less affected by migration rate.

Eccentricity thresholds increase with faster migration, greater distance, and higher resonance order.

Derived empirical formulas enable calculation of capture likelihood based on orbital parameters.

Abstract

Resonant populations of trans-Neptunian objects serve as crucial dynamical archives for unraveling the early migratory history of the Solar System. A quantitative assessment of the capture efficiency into various mean motion resonances (MMRs) during migration is essential for understanding the origins of these populations, constraining migration parameters, and reconstructing of the primordial planetesimal disk. Using numerical simulations, this study systematically investigates the capture capability of exterior MMRs during Neptune's outward migration in a planar model. For a specific p:q MMR, the small bodies can be captured only when their eccentricities surpass a certain threshold, which increases with faster migration rates, greater distances of MMRs, and higher resonance orders. On the other hand, as long as a particle's eccentricity is suitable, its capture efficiency shows little dependence on the migration rate; instead, it mainly depends on the p value and heliocentric distance, decaying exponentially as either parameter increases. Based on our simulation results, we derive for the first time a simple empirical expression to calculate eccentricity threshold and the capture efficiency. This research provides a systematic quantitative framework for understanding capture into Neptunian MMRs during migration. Future integrations of more comprehensive observational data will facilitate a more precise reconstruction of the Solar System's early dynamical evolution.