Comparison with Galaxy Data

The chief motivation behind our modeling efforts is to develop tools to constrain the history of star formation and chemical enrichment of galaxies from analysis of their integrated spectra. In this Section we briefly discuss the comparison between our models and a few high quality data sets of line indices measured in integrated spectra of galaxies. We are aware of the fact that matters become far more complicated when one makes the transition from clusters to galaxies, so we do not intend to discuss these comparisons exhaustively, to avoid lengthening what is already a very long paper. So we just discuss some general trends coming from a comparison of our models to data from the literature, as a prelude to a more in-depth analysis of very-high S/N data for nearby galaxies, which will be presented in a forthcoming paper.

Galaxies are complex systems that have undergone a more prolonged history of star formation than that of globular clusters. Therefore, they are liable to host a mixture of stellar populations of different ages and metallicities. Yet we are comparing them with models for single-burst stellar populations. Therefore, any time we refer to ages and metal abundances in this Section what we really mean is the luminosity-weighted mean ages and metal abundances.