Electron density, n_e, maps derived from the [Sii]λλ6717/6731 line ratios in units of cm^-3. Orientations and sizes as in Fig. 2. On the bottom the statistical frequency distributions with a binning of 100 cm^-3. The edge pointing is on the left, and the central on the right. The white lines across the maps (from NE to SW) represent the direction along which the cuts were extracted to study the radial variation of n_e. See text for details.