Combined plot of the velocity and magnetic field measurements obtained from the 6.7 GHz CH₃OH maser cloudlets (dots) in G023.01−00.41. The axes are aligned with the outflow and disk directions, as defined by the subarcsecond SMA observations in the 1 mm band from Sanna et al. (2014). The origin is set at the HMC center, as defined in Sect. 3 (star symbol in Fig. 2). The dark gray area indicates the region where emission from a flared disk with axes ratio of 1/2 is expected. The light gray area shows the region close to the outflow axis that is devoid of maser emission. For each maser cloudlet, the local directions of the velocity vector (red solid arrows) and/or that of the magnetic field vector (black solid lines) are reported where available. Empty dots are used for cloudlets that do not show polarized emission. The local average of both the magnitude and direction of the velocity field is indicated by red dotted arrows. These values were derived by grouping close-by features with similar velocity directions. The different regions identified through the polarization vectors analysis (Fig. 3) and labeled from 1 to 3 are indicated. For regions showing a smooth variation in the polarization (and magnetic) field vectors with the maser cloudlet position, we plot the families of curves (black dotted lines) that match the tangent to the local magnetic field measurements best (see Sect. 4). The pattern of these families of curves approximates the spatial morphology of the magnetic field lines locally. The direction of the velocity vectors is on average tilted by 30° with respect to the local magnetic field direction.