The correlation between [Mg/Fe] and galaxy mass found in elliptical galaxies imposes a strong constraint on the duration of star formation. Furthermore, the colour-magnitude relation restricts the range of ages and metallicities of the stellar populations. We combine these two constraints with a model of star formation and chemical enrichment including infall and outflow of gas to find that the trend towards supersolar [Mg/Fe] in massive ellipticals excludes a pure metallicity sequence as an explanation of the colour-magnitude relation. An age spread from galaxy to galaxy is thereby required, attributable either to a range of star formation efficiencies (Ceff) or to a range of infall time-scales (τf). We find that the inferred range of stellar ages is compatible with the small scatter and the redshift evolution of the colour-magnitude relation. Two alternative scenarios can explain the data: a fixed τf with a mass-dependent efficiency, Ceff∝M; or a fixed Ceff with mass-dependent infall, . We conclude that the actual scenario may well involve a combination of these two parameters, with mass dependences that should span the range of those given above.
No takes yet. Share an insight, caveat, or question.
Ferreras et al. (2003) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: