Effects of turbulent diffusion and back-reaction on the dust distribution around two resonant planets

TL;DR

This study uses high-resolution hydrodynamical simulations to investigate how turbulent diffusion and dust backreaction influence dust distribution features around two resonant planets, confirming some features remain robust despite these effects.

Contribution

The paper demonstrates through simulations that turbulent diffusion and dust backreaction modify dust morphology but do not eliminate key features like the outer dust peak and inner cavity.

Findings

Dust peaks at the outer edge of the gas gap persist despite diffusion and backreaction.

An expanding dust cavity forms inside the planets' orbits, unaffected by turbulence and backreaction.

Main dust distribution features are robust across different gas viscosity parameters.

Abstract

In evolved and dusty circumstellar discs, two planets with masses comparable to Jupiter and Saturn that migrate outwards while maintaining an orbital resonance can produce distinctive features in the dust distribution. Dust accumulates at the outer edge of the common gas gap, which behaves as a dust trap, where the local dust concentration is significantly enhanced by the planets outward motion. Concurrently, an expanding cavity forms in the dust distribution inside the planets orbits, because dust does not filter through the common gaseous gap and grain depletion in the region continues via inward drifting. There is no cavity in the gas distribution because gas can filter through the gap, although ongoing gas accretion on the planets can reduce the gas density in the inner disc. Such behaviour was demonstrated by means of simulations neglecting the effects of dust diffusion due to turbulence and of dust backreaction on the gas. Both effects may alter the formation of the dust peak at the gap outer edge and of the inner dust cavity, by letting grains filter through the dust trap. We performed high resolution hydrodynamical simulations of the coupled evolution of gas and dust species, the latter treated as pressureless fluids, in the presence of two giant planets. We show that diffusion and backreaction can change some morphological aspects of the dust distribution but do not alter some main features, such as the outer peak and the expanding inner cavity. These findings are confirmed for different parametrizations of gas viscosity.