Constraints on the physical origin of large cavities in transition disks from multi-wavelength dust continuum emission

TL;DR

This study investigates the physical mechanisms behind large cavities in transition disks by analyzing multi-wavelength dust continuum data, revealing potential origins such as companions or grain growth.

Contribution

It provides a comparative analysis of observational signatures and models to constrain the physical origins of cavities in six transition disks.

Findings

Cavities in UXTau A, LkCa15, RXJ1615 may be caused by dust traps from companions.

Cavities in CQTau, SR24S, DMTau could result from pressure bumps and grain growth.

Multi-wavelength data helps distinguish between different cavity formation mechanisms.

Abstract

The physical origin of the large cavities observed in transition disks is to date still unclear. Different physical mechanisms (e.g., a companion, dead zones, enhanced grain growth) produce disk cavities of different depth, and the expected spatial distribution of gas and solids in each mechanism is not the same. In this work, we analyze the multi-wavelength interferometric visibilities of dust continuum observations obtained with ALMA and VLA for six transition disks: CQTau, UXTau A, LkCa15, RXJ1615, SR24S, and DMTau, and calculate brightness radial profiles, where diverse emission morphology is revealed at different wavelengths. The multi-wavelength data is used to model the spectral energy distribution and compute constraints on the radial profile of the dust surface density, maximum grain size, and dust temperature in each disk. They are compared with the observational signatures expected from various physical mechanisms responsible for disk cavities. The observational signatures suggest that the cavities observed in the disks around UXTau A, LkCa15, and RXJ1615 could potentially originate from a dust trap created by a companion. Conversely, in the disks around CQTau, SR24S, DMTau, the origin of the cavity remains unclear, although it is compatible with a pressure bump and grain growth within the cavity.