Spectra of the main components of the PJ308–21 system, integrated over the apertures shown in Fig. 1 (left). For the sake of clarity, spectra are shifted vertically. The spectra are ordered by increasing right ascension of the components: The west companion (blue, at the bottom), the bridge (cyan), the quasar host galaxy (green), the outflow (orange), and the east companion (red). Main emission lines are labeled in gray. The rest-frame is set to the barycenter of the system at z = 6.2342. Thin, lighter lines show the original spectra, while thicker and darker lines show the spectra after convolution with a gaussian, with the sole purpose of increasing the readibility of the plot. The west companion shows extremely high equivalent widths (> 1000 Å) in the main emission lines. A faint stellar continuum is also visible for both the east and the west companions.