The importance of spheroidal and mixed mergers for early-type galaxy formation

We use semianalytical modeling techniques to investigate the progenitor morphologies of present-day elliptical galaxies. We find that, independent of the environment, the fraction of mergers of bulge-dominated galaxies (early types) increases with time. The last major merger of bright present-day elliptical galaxies with M(B)less than or similar to-21 was preferentially between bulge-dominated galaxies, while those with M(B)similar to-20 have mainly experienced last major mergers between a bulge-dominated and a disk-dominated galaxy. Independent of specific model assumptions, more than 50% of present-day elliptical galaxies in clusters with hM(B)less than or similar to-18 had major mergers that were not of spiral galaxies, as usually expected within the standard merger scenario.