Top: median 2D spectra of stars (top row) and pBzKs in the range z = 1.2−1.5 (bottom row), in the same wavelength range and using the same relative flux scale. Prominent features in the stacked galaxy spectrum are indicated in green. The red and cyan lines show the inner and outer extraction apertures, respectively. Bottom: cross-dispersion profile of the stacked pBzK spectrum at 3650−4050 Å rest-frame (dark histogram with gray errors), fit with a combination of a point-source (red) and a Gaussian (blue) profile. The inner and outer extraction apertures are indicated by the orange and light blue shaded regions, respectively. Panels A) and B) show, respectively, the cross-dispersion profiles before and after correcting for galaxy morphology. Only the profile shown in panel A) was used for the decomposition and analysis described in Sect. 3.1 and below.