Distributions of cluster emission derived for simulations with varying free-fall time scaling factor and star formation efficiency ε_SF. The vertical dashed lines correspond to the median flux of each distribution and a measure of central tendency in form of IQR is presented in the bottom box plots with whiskers spreading from the beginning (0%) to the end (100%) of each distribution. These are the mean distributions from a series of ten simulations for each varying pair of and ε_SF. The y- and x-axes have the same ranges for all rows and columns. The color-coding is based on the integrated fluxes of each distribution. The exact values of these fluxes are available in Fig. A.1.