Merger fraction as a function of log ₁₀   μ. We use these particular axis to facilitate the visualization. The dots and the error bars are the observational data. The gray areas are the 1σ confidence intervals of the simulated merger fractions, while the horizontal black lines are their mean (see text for details). Top panel: Merger fraction for  kpc at z_r,2. Bottom panel: Merger fraction for  kpc at z_r,1. (A colour version of this plot is available in electronic form.)