In models of hierarchical galaxy formation ellipticals form through the merging of smaller disk systems (e.g., Kauffmann, White and Guiderdoni,1993). Such models predict that galaxies in low-density environments form later than their counterparts in clusters, and more massive galaxies form later (Kauffmann, 1996). Here we present simulations based on semi-analytic models that include the chemical enrichment of the elements magnesium andiron. The chemical evolution code is described in Thomas, Greggio and Bender(1998, 1999). The results are: 1) The Mg/Fe predicted for elliptical galaxies does not agree with the values derived from observations. 2) The most luminous (and massive) ellipticals have the lowest Mg/Fe, in conflict with the observational evidence. 3) Galaxies in looser environments exhibit lower Mg/Fe ratios. 4) Bulges are most α-enhanced independent of the environment. For more details I refer the reader to Thomas (1999) and Thomas and Kauffmann (1999).
- galaxies : elliptical and lenticular,m cD
- galaxies : abundances
- galaxies : formation
- galaxies : evolution
- cosmology : theory