OSSOS. XIII. Fossilized Resonant Dropouts Tentatively Confirm Neptune’s Migration Was Grainy and Slow

Abstract

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 2σ 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.

A search of the full six years of the Dark Energy Survey for outer Solar System objects

“…This process is sensitive to the smoothness and speed of Neptune's migration (see detailed discussion in Kaib & Sheppard 2016). We conduct a similar test to the one presented in Lawler et al (2019), who found marginal inconsistency (p-value ≈ 0.029) of the OSSOS TNOs near the 5:2 and 4:1 resonances with q > 40 au arising from uniform distribution in period P ≡ a 3/2 .…”

“…We select the 16 non-resonant, non-scattering objects with q > 38 au (so a larger sample can be obtained) within ±2 au of the 5:2 (2 objects, all sunward), 3:1 (7 objects, 5 sunward), 7:2 (3 objects, all sunward) and 4:1 (4 objects, all sunward) resonances, and test whether the sample is consistent with a distribution uniform in P (as in Lawler et al 2019), as well as a distribution p(a) ∝ a −5/2 (as in the hot and stirred components of the CFEPS model). We define…”

GLISSE: A GPU-optimized planetary system integrator with application to orbital stability calculations

“…There are again particles which diffuse out of the resonance over the 4 Gyr and are found either just beyond the borders at low e or in the detached population on either side with e ≈ 0.35. Curiously, this integration exhibits slightly more objects on the low-a side of the resonance; if not chance, this might influence conclusions related to this asymmetry being caused by dropouts during the final stages of planetary migration [33].…”

Planetary Astronomy-Understanding the Origin of the Solar System

“…Current large dynamical simulations are testing whether OSSOS observational data can lend support to or rule out different migration timescales, aand if it can place limits on the number of large planetesimals that were present at the time of Neptune's migration (e.g. Lawler et al, 2019).…”