Coherent cores, as defined in Sect. 3.2, are shown by black contours. The background colour scale shows the sonic Mach number. The dashed rectangle shows the box considered to be representative of the ambient cloud. The red stars show positions of Class 0/I and flat-spectrum protostars in the cloud (Dunham et al. 2015). The beam and the scale bar are shown in the bottom left and bottom right corners, respectively.