On the left panel, CCF results for two single SMBHs and a simulated binary given by the spectra presented in Fig. C.3, as a function of different fractions of the total BEL luminosity in the blue part of the line. On the right panel, the corresponding time delays, i.e. the time shifts that maximize the correlation coefficient. Since the BLR extends from 200 − 1800 r_G ∼ 1 − 10 ld, the expected delays between the blue part and the red part of the line are of order of only a few days. The monotonic decrease of the time delay with respect to the blue fraction in the single SMBH case reflects that the line wings, which arise at smaller radii, respond faster. To better visualize this shorter delays, the right panel is shown with a restricted vertical range (−10 to 10 d).