The authors discuss in their paper (Feldmann et al. 2010; arXiv:1008.3386) a recent high resolution cosmological hydro simulation of the formation of a galaxy group environment. The remarkable feature of their simulation is to be able to resolve the detailed formation history of individual group members with high mass resolution (SPH particle mass = 1E6 M_sun). Their main conclusion is that elliptical galaxies form by major mergers before the assembly of the group, and that gas cooling and associated star formation is strongly suppressed via ram-pressure stripping once galaxies enter the group environment.
I think it is a clear step forward to simulate groups within a cosmological setting with high resolution. However, I think the authors could have shown more detailed comparisons to the properties of locally observed elliptical galaxies. In particular comparisons to SAURON observations or the work of Bender et al or Faber et al would have been useful. This would have helped to strengthen their claims on the formation of ellipticals. One point that I am very curious about is the metallicities, and in particular the alpha/Fe abundance of their simulated ellipticals.
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