Demonstration of the median composite spectra of background quasars in different d_p bins as shown in each of panel. The black and green lines represent the Mg IIλ2796 and Fe IIλ2600 absorption line profiles, respectively. The black and green dashed lines represent the standard deviation of the normalized flux density for Mg IIλ2796 and Fe IIλ2600, respectively. The gray shaded regions mark the spectral region used for measuring the equivalent widths of the Mg IIλ2796 or Fe IIλ2600 absorption lines.