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Magneto-centrifugal (MC) disk-winds (DW) are accredited to connect accretion and ejection in different astrophysical objects, from forming stars to supermassive black holes. Despite their fundamental importance, direct observations of DWs, that is imaging of the corresponding velocity and magnetic fields, are still lacking. High-mass young stellar objects (YSO) could provide the only environment where DW operation can be presently studied, through VLBI of the intense 22 GHz water masers, as proved by our recent Protostellar Outflows at the EarliesT Stages (POETS) survey. Our goal is to test the MC DW scenario in G092.69+3.08, the massive YSO belonging to the POETS survey with the strongest evidence for jet rotation, hinting at MC acceleration. We propose sensitive (rms 1~mJy/beam on the maser linewidth of 0.2 km/s), polarimetric Global VLBI observations to target the weaker but conspicuous maser population predicted by the POETS results. Tracing the maser velocities within 100 au from the YSO (to establish whether the jet rotation stems from the disk), and measuring the sky-projected orientation of the magnetic field (to check whether the wind flows along the magnetic field lines), we can critically test the MC DW models. |