A multi-fluid approach for pebble accretion

Pebble accretion is widely considered a key, and probably necessary, ingredient for rapid planet formation. However, most studies still rely on simplified gas prescriptions or assume a single particle size (monodisperse). For this work, we revisit pebble accretion using a multi-fluid hydrodynamical model that evolves the gas and multiple pebble species (polydisperse) self-consistently. This allows us to move beyond static background discs and directly study how the planet’s perturbation of the gas affects the accretion of solids. We find that perturbing the disc modifies the accretion efficiency systematically with Stokes number. We find lower total accretion because of this perturbation of the gas. Interestingly, we see the ratio between poly-, and monodisperse accretion to be significantly higher than previous estimations. These results demonstrate the importance of self-consistent gas evolution, not only for polydisperse pebble accretion, but also for understanding the transition from pebble accretion to isolation and gap opening.