First-principles theory of massive-planet migration

Develop a successful first-principles explanation for the migration of massive, gap-opening planets in protoplanetary disks that captures the highly non-linear disk–planet interactions and predicts migration behavior without reliance on empirical fitting or type-II assumptions tied to viscous drift.

Background

Massive planets carve gaps in protoplanetary disks, altering local surface density and thereby changing migration torques relative to the low-mass (type-I) regime. Historically, type-II migration assumed that gap-opening planets migrate with the viscous drift of the disk, but this picture is refuted by numerical experiments showing continued mass flow across planetary gaps and migration not locked to viscous evolution.

Recent work provides semi-empirical torque and migration scalings for gap-opening planets by relating the torque to the density at the bottom of the gap; however, a comprehensive, predictive theory derived directly from the governing hydrodynamics and gravity, and able to handle the strongly non-linear nature of the problem, is lacking. The chapter explicitly acknowledges that a fully first-principles explanation remains out of reach.