Positions of sub-regions in the image and source planes. Left panel: Labels of the main rest-UV peaks and subregions of the D1-T1-UT1 systems on the stack of the SW filter observations. The inset shows a stacking of all filters where the three main regions (D1, T1 and UT1) are delimited by the red contours, while larger contours enclosing also the low surface-brightness emission are shown in green. Right panel: Mapping of the main and subregion positions on the source plane at z = 6.145 obtained from the best-fitting lens model by Bergamini et al. (2023). The compact cores (D1_core, T1_core and UT1a) are marked by white filled circles, while the other peaks of UV emission are marked by white “X” symbols. A 1 kpc (0.17″) reference scale is given in the top left corner. The FWHM of the F200W is also given as reference. The location of T1_core coincides with the peak of the Lyα emission introduced in Sect. 1. The bridge region refers to the region of faint line emission discussed in Sect. 3.5.