Planet filtering at the inner edges of dead zones in protoplanetary disks

Abstract

Context. The interface between the dead zone and the inner active zone in a protoplanetary disk provides a promising region where the inward migration of planets may be halted owing to the existence of strong corotation torques. Recent work has indicated that this region may be prone to supporting a vortex cycle, during which vortices form at the dead-active zone interface and migrate into the active region before being destroyed, after which a new vortex forms and the cycle repeats. Aims. The aim of this paper is to examine the interaction between migrating planets and this vortex cycle, and to determine the conditions under which planets are able to remain trapped at the dead-active zone interface. Methods. We use the magnetohydrodynamics (MHD) codes PLUTO and RAMSES to perform 2D viscous disk simulations and 3D MHD simulations of protoplanetary disks containing migrating planets. A temperature switch is used to control the e↵ective viscosity at the dead-active zone interface. Results. We find that both low mass and non-gap forming higher mass planets are able to escape from the planet trap at the inner edge of the dead zone as a result of their interaction with the migrating vortices, whereas intermediate mass planets remain trapped for the duration of simulation run times. Conclusions. Our results indicate that the vortex cycle causes the dead zone inner edge to act as an e↵ective and mass-dependent planet filter, allowing some planets to pass through this region and others to remain there over long timescales.