2024A&A...686A.201N

Protostellar disks are known to accrete; however, the exact mechanism that extracts the angular momentum and drives accretion in the low-ionization “dead” region of the disk is under debate. In recent years, magnetohydrodynamic (MHD) disk winds have become a popular solution. Even so, observations of these winds require both high spatial resolution (∼10 s au) and high sensitivity, which has resulted in only a handful of MHD disk wind candidates to date. In this work we present high angular resolution (∼30 au) ALMA observations of the emblematic L1448-mm protostellar system and find suggestive evidence for an MHD disk wind. The disk seen in dust continuum (∼0.9 mm) has a radius of ∼23 au. Rotating infall signatures in H¹³CO⁺ indicate a central mass of 0.4 ± 0.1 M_⊙ and a centrifugal radius similar to the dust disk radius. Above the disk, we identify rotation signatures in the outflow traced by H¹³CN, CH₃OH, and SO lines and find a kinematical structure consistent with theoretical predictions for MHD disk winds. This is the first detection of an MHD disk wind candidate in H¹³CN and CH₃OH. The wind launching region estimated from cold MHD wind theory extends out to the disk edge. The magnetic lever arm parameter would be λ_ϕ ≃ 1.7, in line with recent non-ideal MHD disk models. The estimated mass-loss rate is approximately four times the protostellar accretion rate (Ṁ_acc ≃ 2 × 10^–6M_⊙ yr^–1) and suggests that the rotating wind could carry enough angular momentum to drive disk accretion.