Expected incidence of dual active BH in equal-mass mergers of spiral galaxies (of Sb type) in the nearby universe, as a function of the merger timescale, τ_mer. P_dagn is the intrinsic fraction of binary mergers with active BH pairs and P_dagn, spec is the fraction of these mergers observable through double-peaked narrow line features in the optical window. The panels on each column show results for different representative thresholds of nuclear activity (see text). Top panels: results for a BH lifetime, τ_agn, of 10² Myr, while bottom panels: results for τ_agn = 10 Myr. Individual predictions are represented with green dots, while large red open circles and error bars show the median and interquartile range of the subsets of results inferred from the same initial orbital eccentricity, ϵ, which increases from left to right in each panel. This figure is for mergers starting with a reduced orbital energy r_circ, p = 4/3.