How two-dimensional are planet-disc interactions? II. Radiation hydrodynamics and suitable cooling prescriptions

Abstract

The ring and gap structures found in observed protoplanetary disks are often attributed to embedded gap-opening planets and typically modeled with simplified thermodynamics in the 2D, thin disk approximation. However, it has been shown that radiative cooling and meridional processes play key roles in planet-disk interaction, though their computational cost has limited their exploration. We investigate the differences between 2D and 3D models of gap-opening planets while also comparing thermodynamical frameworks ranging from locally isothermal to fully radiative. We also compare simplified cooling recipes to fully radiative models in an effort to motivate the inclusion of radiative effects in future modeling even in a parametrized manner. We perform hydrodynamical simulations in both 2D and 3D, and then compare the angular momentum deposition by planetary spirals to assess gap opening efficiency. We repeat comparisons with different thermodynamical treatments: locally isothermal, adiabatic, local beta cooling, and fully radiative including radiative diffusion. We find that 2D models are able to capture the essential physics of gap opening with remarkable accuracy, even when including full radiation transport in both cases. Simple cooling prescriptions can capture the trends found in fully radiative models, albeit slightly overestimating gap opening efficiency near the planet. Inherently 3D effects such as vertical flows that cannot be captured in 2D can explain the differences between the two approaches, but do not impact gap opening significantly. Our findings encourage the use of models that include radiative processes in the study of planet-disk interaction, even with simplified yet physically motivated cooling prescriptions in lieu of full radiation transport. This is particularly important in the context of substructure-inducing planets in the ALMA-sensitive disk regions (>10 au).