High-resolution [OI] line spectral mapping of TW Hya consistent with X-ray driven photoevaporation

TL;DR

This study demonstrates that X-ray driven photoevaporation models accurately reproduce the spectral line profiles and luminosities observed in TW Hya, suggesting photoevaporative winds dominate disk dispersal over MHD winds.

Contribution

The paper shows that state-of-the-art X-ray driven photoevaporation models can explain the observed spectral features of TW Hya better than MHD wind models.

Findings

Photoevaporation models match the compact [OI] emission and line profiles.

Models reproduce observed line luminosities of [OI] and [NeII].

MHD models fail to match spectral profiles and underestimate [NeII] luminosity.

Abstract

Theoretical models indicate that photoevaporative and magnetothermal winds play a crucial role in the evolution and dispersal of protoplanetary disks and affect the formation of planetary systems. However, it is still unclear what wind-driving mechanism is dominant or if both are at work, perhaps at different stages of disk evolution. Recent spatially resolved observations by Fang et al. (2023) of the [OI] 6300 Angstrom spectral line, a common disk wind tracer, in TW Hya revealed that about 80% of the emission is confined to the inner few au of the disk. In this work, we show that state-of-the-art X-ray driven photoevaporation models can reproduce the compact emission and the line profile of the [OI] 6300 Angstrom line. Furthermore, we show that the models also simultaneously reproduce the observed line luminosities and detailed spectral profiles of both the [OI] 6300 Angstrom and the [NeII] 12.8 micron lines. While MHD wind models can also reproduce the compact radial emission of the [OI] 6300 Angstrom line, they fail to match the observed spectral profile of the [OI] 6300 Angstrom line and underestimate the luminosity of the [NeII] 12.8 micron line by a factor of three. We conclude that, while we cannot exclude the presence of an MHD wind component, the bulk of the wind structure of TW Hya is predominantly shaped by a photoevaporative flow.