UV spectra reproduced from Brown et al. (2002, their Fig. 1). Observations taken with Hubble’s Space Telescope Imaging Spectrograph (STIS) using the G140L grating and the 52″ × 0$\stackrel{″}{.}$5 slit. The two spectra (bottom) were taken from two clusters in the north-western region that contain C IV bumps (top, where Xs mark the approximate positions from which those spectra were extracted; see our Fig. 14 where these positions are more reliably pinpointed by the authors themselves). Note the presence of He II bumps, which are similar in size to the C IV bumps, consistently with out models (see Sect. 4.2).