Left panel: observed-frame spectrum at the Lyα wavelength of the AzTEC-3+LBG-3 system in the vacuum. The observed spectrum is shown as data points with error bars and the smoothed spectrum as a black curve like in Fig. 9. The best-fit zELDA model that corresponds to the 50th percentile is shown in green and the green shaded area contains the models within the 16th and 84th percentiles obtained fitting the spectrum at wavelength larger than the systemic redshift. In blue, we show the models obtained fitting the spectrum only at the wavelength larger than the maximum. The red curve corresponds to the best fit in the wavelength range 7630−7700 Å for the AzTEC-3+LBG-3 spectrum corrected for the IGM absorption, by using the prescription of Madau (1995). Right panel: best-fit zELDA models for the spectra extracted in a 0.7″ aperture located on the position of the main Lyα emission associated to AzTEC-3 (upper left), the position of the UV knots of the SMG (upper right), the position of the main Lyα emission associated to LBG-3 (lower left), and the bridge between SMG and LBG (lower right). Black dots with error bars are the observed-frame spectra as shown in Fig. 9, the black lines are the smoothed spectra, the green (blue) curves and shaded areas are the best-fit models and the models within the 16th and 84th percentile of the model parameter space obtained fitting the spectra at wavelength larger than the systemic redshift (larger than 7669 Å). Vertical blue dashed lines indicate the Lyα redshift given by the AzTEC-3 [C II] detection. The zELDA fits are performed fixing the redshift to the systemic inferred by the [C II] emission peak.