The color maps are the same as in Fig. 14, while the superimposed solid blue and dashed red contours represent, respectively, the blueshifted emission and redshifted absorption seen in the ¹³CO (left panel) and C¹⁸O (right panel). To obtain these plots, we integrated the line over 3 velocity channels centered on the deepest absorption and the most intense emission, namely over the ranges: 34.2  ≤ V_LSR/km s^-1  ≤  35.8 for the blueshifted ¹³CO emission, 43.8  ≤ V_LSR/km s^-1  ≤  45.0 for the redshifted ¹³CO absorption, and 36.0  ≤ V_LSR/km s^-1  ≤  38.4 for the blueshifted C¹⁸O emission, 44.0  ≤ V_LSR/km s^-1  ≤  46.4 for the redshifted C¹⁸O absorption. These velocity ranges are outlined by the horizontal blue and red bars in Fig. 7. All the contours are in steps of  ± 2σ and start from the  ± 3σ level. The stars mark the peak positions of SMA1 and SMA2. See Sect. 4.2 for details.