X-shooter spectrum in the bottom of saturated lines at z > z_dla (black, with error spectrum in grey). The orange dashed curve raising at  ~3930–3940 Å shows the bottom of synthetic Voigt profile with log N(H   i) = 22.10. The green spectrum is the LBG composite spectrum from Kornei et al. (2010), scaled to match the integrated Ly α emission line. Note that the Ly α emission line is commonly diminished in the blue for LBGs, resulting in the apparent shift of the composite Ly α line towards redder wavelengths. Blue lines are synthetic stellar continua calculated with starburst99 (Leitherer et al. 1999), using a Salpeter IMF, metallicity Z = 0.004, and continuous SFR = 25   M_⊙ yr^-1 since respectively, 100 Myr (dotted), 10 Myr (dashed), 1 Myr (solid). Horizontal segments illustrate the mean fluxes in the corresponding regions. Note that in the case of the line at  ~4495 Å, the Ly α absorption is partially blended with Si iv λ1402 from the DLA. The blended region (4497–4500 Å) is therefore not considered to compute the mean.