The interplay between forming planets and photoevaporating discs II: Wind-driven gas redistribution

Abstract

Disc winds and planet-disc interactions are two crucial mechanisms that define the structure, evolution and dispersal of protoplanetary discs. While winds are capable of removing material from discs, eventually leading to their dispersal, massive planets can shape their disc by creating sub-structures such as gaps and spiral arms. We study the interplay between an X-ray photoevaporative disc wind and the substructures generated due to planet-disc interactions to determine how their mutual interactions affect the disc's and the planet's evolution. We perform three-dimensional hydrodynamic simulations of viscous ($α= 6.9\cdot10^{-4}$) discs that host a Jupiter-like planet and undergo X-ray photoevaporation. We trace the gas flows within the disc and wind and measure the accretion rate onto the planet, as well as the gravitational torque that is acting on it. Our results show that the planetary gap takes away the wind's pressure support, allowing wind material to fall back into the gap. This opens new pathways for material from the inner disc (and part of the outer disc) to be redistributed through the wind towards the gap. Consequently, the gap becomes shallower, and the flow of mass across the gap in both directions is significantly increased, as well as the planet's mass-accretion rate (by factors $\approx 5$ and $\approx 2$, respectively). Moreover, the wind-driven redistribution results in a denser inner disc and less dense outer disc, which, combined with the recycling of a significant portion of the inner wind, leads to longer lifetimes of the inner disc, contrary to the expectation in a planet-induced photoevaporation (PIPE) scenario that has been proposed in the past.