Expected numbers of detectable GW events generated during the last day before the merger in a year of observation by LISA (left panels) and AEDGE (right panels) as functions of the chirp mass ℳ₀ and redshift z (upper panels) and of chirp mass and symmetric mass ratio η (lower panels). The merger rates assume the abundance of IMBHs described by Eq. (6) for BHs heavier than 10³ M_⊙ and a universal merger efficiency factor of p_BH = 0.17 inferred from the IPTA data.