Zoom on the cores MM3 and MM4 with the relative subcores. Left panel: the contours represent linearly polarised emission and the levels are (0.3, 0.5, 1.0, 1.5, 2.0) mJy beam⁻¹. Right panel: the segments indicate linear polarisation vectors already rotated of 90° to show the orientation of the magnetic field. Only in this figure, the sampling of the vectors are every 165 by 165 mas. In both, the offsets are relative to the same position as in Fig. 3 and the colour scale indicates the total intensity of the background image in Jy beam⁻¹, going from −0.01 to 0.45 Jy beam⁻¹; the yellow bar indicates the physical scale of 0.05 pc, at the distance of the source.