Figure 2. An example of a galaxy merger history. The galaxy has a stellar mass M∗ = 1.7× 1011 M at redshift z = 0. Symbol colours and sizes are logarithmically scaled with stellar mass. The thick solid line marks the main branch. The final galaxy is built from many small progenitors, but most of these contributors have very low mass. We also show images of its stellar mass distribution in a 200 comoving kpc box at a few redshifts. The galaxy shows prominent spiral-like structure at redshift z = 1, but then experiences several interactions with other objects, passing through a shell-like phase to transform into an elliptical galaxy at z = 0.
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