Magnetic disk winds in protoplanetary disks

Description of the model and impact on global disk evolution

¹ Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, 8042 Graz, Austria
² Department of Astrophysics, The University of Vienna, 1180 Vienna, Austria
³ Department of Physics and Astronomy, University of Western Ontario, London, Ontario N6A 3K7, Canada
⁴ Institute for Earth & Space Exploration, University of Western Ontario, London, Ontario N6A 5B7, Canada

^★ Corresponding author; kundan.kadam@oeaw.ac.at

Received: 4 April 2024
Accepted: 30 January 2025

Abstract

Context. Canonically, a protoplanetary disk is thought to undergo (gravito-)viscous evolution wherein the angular momentum of the accreting material is transported outward. However, several lines of reasoning suggest that the turbulent viscosity in a typical protoplanetary disk is insufficient to drive the observed accretion rates. An emerging paradigm suggests that radially extended magnetic disk winds, which transport angular momentum vertically, may play a crucial role in disk evolution.

Aims. We propose a global model of magnetic wind-driven accretion for the evolution of protoplanetary disks in the thin-disk limit based on the insights gained from local shearing box simulations. In this paper, we aim to develop this model and constrain the model parameters with the help of theoretical expectations and through comparison with observations.

Methods. The magnetic wind is characterized with the associated loss of angular momentum and mass, and we modeled these with fitting formulae that depend on the local disk conditions and stellar properties. We incorporated the disk winds self-consistently in the numerical magnetohydrodynamic code FEOSAD and studied the formation and long-term evolution of protoplanetary disks. We included disk self-gravity and an adaptive turbulent α that depends on the local ionization balance, while the co-evolution of a two-part dusty component was also considered. We obtained synthetic observations via detailed modeling with the radiation thermo-chemical code PRODIMO.

Results. The models that include disk winds satisfy the general expectations from both theory and observations. The disk wind parameters can be guided by observational constraints, and the synthetic observations resulting from such a model compare favorably with the selected ALMA survey data of Class II disks. The proposed magnetic disk wind model is a significant step forward in the direction of representing a more complete disk evolution, wherein the disk experiences concurrent torques from viscous, gravitational, and magnetic wind processes.