Light curves and their FFT for circular mass binaries at z = 0.1. The left and right panels are for binaries with q = 1 and q = 0.1, respectively. In each panel, the first row shows the accretion rate (grey line) and the flux (orange line) integrated over the whole frequency range we consider (10⁸ − 2.8 × 10¹⁹ Hz). The left column shows the flux evolution in time while the right column shows the FFT of the accretion rate and flux over 300 orbits in the time window t = 1000 − 1300 P_B (left panel) or t = 760 − 1060 P_B (right panel), normalised to unity, in function of f/f_K with f_K the Keplerian frequency of the binary. The second, third, and fourth rows show the flux and FFT in the optical Z band, UV band, and soft X-ray band, respectively. The optical flux was computed taking into account an extra Gaussian noise component, as is described in Sect. 2.2.