Galaxy half-light radius as a function of its final V -band luminosity (L_V). The blue hexagons show the model predictions at z = 0 (top panel) or soon after the end of the star formation activity (bottom panel). The Milky Way and M31 satellites are identified with black squares and triangles, respectively. For clarity, we only label galaxies with extreme half light radius, larger than 1 kpc or smaller than 200 pc.