Effective radius R_e–stellar mass M relation produced by the merging of gas‐rich disk galaxies with dark matter halos, star formation and supernova feedback. Shown are remnants produced by mergers appropriate for redshifts ﹩z=0﹩ (black circles), ﹩z=2﹩ (red diamonds), ﹩z=3﹩ (blue triangles), and ﹩z=6﹩ (green squares) with nearly radial, parabolic orbits. The dissipational merging of pure disk models produces a R_e‐M relation roughly parallel to that measured for massive galaxies in the SDSS (Shen et al. 2003). For comparison, the best least‐squares fit to the R_e‐M relations delineated by the dissipational simulations (solid line) and dissipationless simulations (dotted line) are plotted. Also shown is the mean deviation induced by line‐of‐sight variations in projected quantities for a given remnant (detached error bars).