Quantifying the Impact of the Dust Torque on the Migration of Low-mass Planets II: The Role of Pebble Accretion in Planet Growth within a Global Planet Formation Model

Abstract

Although dust constitutes only about 1% of the mass of a protoplanetary disk, recent studies demonstrate that it can exert a significant torque on low- and intermediate-mass planetary cores. We compute and quantify for the first time the influence of the dust torque on the evolution of growing planetary embryos as they move in a protoplanetary disk while growing via gas and pebble accretion. Our global model evolves the gaseous disk via viscous accretion and X-ray photoevaporation, while accounting for dust growth and evolution including coagulation, drift, and fragmentation. Our research indicates that dust torque significantly influences planetary migration, particularly driving substantial outward migration for planets forming within the water ice-line. This effect occurs due to an increased dust-to-gas mass ratio in the inner disk, resulting from inward pebble drift from outer regions. In contrast, for planets initially located beyond the water ice-line, the dust torque mitigates inward migration but does not significantly alter their paths, as the dust-to-gas ratio diminishes rapidly due to rapid pebble drift and the brief timescales of planet formation in these areas. These findings underscore the pivotal role of dust torque in shaping the migration patterns of low- and intermediate-mass planets, especially when enhanced dust concentrations in the inner disk amplify its effects