The [CI]/continuum ratio maps are in the upper panels and the [CI]/CO line ratio maps are in the lower panels for SPT0103−45, SPT2147−50 and SPT2357−51, from left to right. The 5, 10, and 15σ contours of the continuum are plotted on the ratio maps (in magenta). The computation of these ratios are described in Sect. 7.1. The synthesised beam is represented as the black ellipse in the bottom left of every map.