History of two merging galaxies, H4 and H98 (dubbed as “a” and “b”) shown in the left panel, reconstructed along their past merger tree, starting from z = 4.5 up to z = 5.1. At each redshift, we show both the main progenitor (black solid line) and secondary progenitor (black dashed lines), we also report the stellar mass ratio μ_⋆ of the primary (green) and secondary (magenta) merging galaxies. In the middle and right panels, we show the projection on the (x, y) plane of the merging galaxies as seen in dark matter and baryonic matter components, respectively. For the sake of clarity, we only show the maps at four redshift steps (z = 5.1, 4.9, 4.7, and 4.5, from top to bottom) and galaxies are color-coded the same way as in the merger tree.