Phase-space spiral of the immediate solar neighbourhood (R_cyl < 500 pc). The three panels show: (a) the stellar number count density in the (Z, W) phase-space plane; (b) a ratio of this histogram with respect to a best-fit smooth and symmetric background distribution; (c) a ratio with respect to the same background distribution, but projected on the Z-axis. The over-densities at Z ≃ 200 pc and Z ≃ −400 pc have clear counterparts in Fig. 6. In panel b, we exclude regions far from the panel centre, where the total number count is low and the statistical noise is high. In panel c, we mask |Z|< 100 pc, where the Gaia radial velocity sample is dominated by strong selection effects due to stellar crowding. Further details are found in the text.