OSSOS: XIII. Fossilized Resonant Dropouts Tentatively Confirm Neptune's Migration was Grainy and Slow

• Main Authors: Lawler, S. M, Pike, R. E, Kaib, N, Alexandersen, M, Bannister, M. T, Chen, Y. -T, Gladman, B, Gwyn, S, Kavelaars, J. J, Petit, J. -M, Volk, K
• Format: Journal Article
• Language: English
• Published: 24-04-2019
• Subjects: Physics - Earth and Planetary Astrophysics
• DOI: 10.48550/arxiv.1808.02618

The migration of Neptune's resonances through the proto-Kuiper belt has been
imprinted in the distribution of small bodies in the outer Solar System. Here
we analyze five published Neptune migration models in detail, focusing on the
high pericenter distance (high-q) trans-Neptunian Objects (TNOs) near Neptune's
5:2 and 3:1 mean-motion resonances, because they have large resonant
populations, are outside the main classical belt, and are relatively isolated
from other strong resonances. We compare the observationally biased output from
these dynamical models with the detected TNOs from the Outer Solar System
Origins Survey, via its Survey Simulator. All of the four new OSSOS detections
of high-q non-resonant TNOs are on the Sunward side of the 5:2 and 3:1
resonances. We show that even after accounting for observation biases, this
asymmetric distribution cannot be drawn from a uniform distribution of TNOs at
2sigma confidence. As shown by previous work, our analysis here tentatively
confirms that the dynamical model that uses grainy slow Neptune migration
provides the best match to the real high-q TNO orbital data. However, due to
extreme observational biases, we have very few high-q TNO discoveries with
which to statistically constrain the models. Thus, this analysis provides a
framework for future comparison between the output from detailed, dynamically
classified Neptune migration simulations and the TNO discoveries from future
well-characterized surveys. We show that a deeper survey (to a limiting
r-magnitude of 26.0) with a similar survey area to OSSOS could statistically
distinguish between these five Neptune migration models.