Electromagnetic properties of MBHBs and their host galaxies for CW candidates. The left panels show B, V, and K magnitudes; the right panels show X-ray flux at [2–10] keV, radio flux at 2 GHz and bolometric luminosity (the horizontal line marks L_bol = 10⁴⁵ erg s⁻¹), as a typical value for quasar luminosities. For MBHs with f_Edd < 10⁻³ we show an optimistic upper limit to the brightness ignoring the correction to radiative efficiency.