R_e‐ M relations produced by the merging of spheroidal galaxy models. The mergers of Hernquist (1990) stellar spheroids initial conditions with dark matter halos (blue triangles), initialized to the Shen et al. (2003) relation (dashed line), with nearly radial, parabolic orbits (black circles) and wide, elliptical orbits with circularity ﹩\epsilon =0.5﹩ (red diamonds) are simulated. The remnants of spheroidal mergers produce a R_e‐M relation slightly shallower than the observed relation, roughly independent of the orbital energy or angular momentum. Also shown are spheroidal remnants from gas‐rich disk galaxy merger simulations that include star formation, supernova feedback, and a prescription for feedback from accreting supermassive black holes (orange squares). The disk galaxy merger remnants occupy a R_e‐M relation with the same scaling as observed in SDSS (dashed line). The remerging of these disk galaxy merger remnants on nearly radial, parabolic orbits (green circles) produces a similar R_e‐M relation as the dissipationless merging of spheroidal galaxies. For comparison, the best least‐squares fit to the R_e‐M relation delineated by the dissipationless spheroidal merger remnants (dashed‐dotted line), the Shen et al. (2003) relation, and the relation produced by simulations using the full physical model (solid 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).