Constraining Migration Models with the 2:1 Resonance

Probability map of the fraction of symmetric island twotinos (fS) and asymmetric twotinos in the leading island (fL), constrained by the observed population fractions of the symmetric and leading asymmetric islands ( fS,OSSOS, fL,OSSOS; i.e., the number of detections in each island should be the same as the ratio in the OSSOS sample). The rejected regions for this probability distribution are indicated with solid (99% confidence level) and dashed (95% confidence) white curves. Note that the absolute probabilities (color map) are low only because the cells have very high resolution; the contours correctly enclose the normalized probabilities. The fS and fL from Chiang & Jordan (2002), Li et al. (2014), Pike & Lawler (2017), and Lawler et al. (2019) are overplotted with dots and labeled.

The orbital structure of the objects in Neptune’s 2:1 mean-motion resonance (“twotinos”) has the potential to be a tracer of planetary migration processes. Different migration processes produce distinct architectures, recognizable by well-characterized surveys. We use the OSSOS twotinos and the survey characterization parameters via the OSSOS survey simulator to inspect the intrinsic population and orbital distributions of twotinos.