Modeling planet-induced gaps and rings in ALMA disks: the role of in-plane radiative diffusion

TL;DR

This paper demonstrates that including in-plane radiative diffusion in models of planet-disk interactions significantly improves the match between simulated and observed ALMA disk structures, highlighting the importance of accurate radiative transfer treatment.

Contribution

It introduces a new modeling approach that incorporates in-plane radiative diffusion, showing its impact on disk morphology and better alignment with ALMA observations compared to local cooling models.

Findings

In-plane radiative diffusion alters the disk's response to spiral waves.

Models with diffusion better reproduce observed rings and gaps.

Proper radiation transport modeling is crucial for interpreting ALMA data.

Abstract

ALMA observations of protoplanetary disks in dust continuum emission reveal a variety of annular structures. Attributing the existence of such features to embedded planets is a popular scenario, supported by studies using hydrodynamical models. Recent work has shown that radiative cooling greatly influences the capability of planet-driven spiral density waves to transport angular momentum, ultimately deciding the number, position, and depth of rings and gaps that a planet can carve in a disk. However, radiation transport has only been treated via local thermal relaxation, not taking into account radiative diffusion along the disk plane. We compare the previous state-of-the-art models of planet-disk interaction with local cooling prescriptions to our new models that include cooling in the vertical direction and radiative diffusion in the plane of the disk, and show that the response of the disk to the induced spiral waves can differ significantly when comparing these two treatments of the disk thermodynamics. We follow up with synthetic emission maps of ALMA systems, and show that our new models reproduce the observations found in the literature better than models with local cooling. We conclude that appropriate treatment of radiation transport is key to constraining the parameter space when interpreting ALMA observations using the planet-disk interaction scenario.