Observations compared with simulations for the magnetic field in the NE and SW regions. Left panel: dots give the water maser positions, using colors (gray) if the magnetic field amplitude has (not) been measured. Black segments show the direction of the magnetic field vector evaluated in correspondence with the masers with detected linear polarization. We note that the observed positions are rotated 50° clockwise so as to align the jet axis with the vertical axis. Right panel: 3D view of four simulated streamlines departing from the launch radius of 4 au at 90° azimuthal separation from one another. The simulation snapshot refers only to the inner jet cavity, within a radius of 40 au. Segments show the direction of the magnetic field vector evaluated at different positions along the streamlines, and the colors indicate the decimal logarithm of the magnetic field intensity.