Constraining Neptune's Migration: Cold Classicals in the 2:1 Resonance?

International audience; The small bodies in the outer Solar System, called trans-Neptunian objects (TNOs), have a variety of surface types and orbital classifications. The cold classicals, which formed in situ, and the dynamically excited objects, which were likely scattered into their current locations, have distinct surface types. These surface types can be robustly identified using photometry in the combination of g, r, and z bands. We investigate the 2:1 resonance, which is located just outside the cold classical belt, to see whether this resonance harbors trapped cold classical surfaces. These would have been captured during a period of smooth sweeping migration by Neptune. We have acquired photometry of 17 of our 34 targets in 2018, and our results exclude a slow smooth sweeping of the entire cold classical region by Neptune's 2:1 resonance.