Abundance Ratios in Composite Stellar Populations with special emphasis on Elliptical Galaxies

Abstract

Our unified chemical and spectrophotometric evolution code allows to simultaneously study the ISM abundances of a series of elements and the spectral properties of the stellar population in our model galaxies. We use stellar evolutionary tracks, yields, spectra, color and absorption index calibrations for 5 different metallicities and account for the increase in initial metallicity of successive generations of stars. For any kind of stellar system, as described by its star formation history and IMF, we thus can directly compare the time evolution of gaseous and stellar abundance ratios. Spiral galaxy models that successfully reproduce spectral properties as well as ISM abundances of nearby templates are combined with a cosmological model and compared to damped Lyman $α$ absorbers. For early type galaxies various formation scenarii -- initial monolithic collapse, spiral-spiral merger, hierarchical formation -- are tested with respect to their predicted spectral energy distributions from UV to NIR and absorption indices and index ratios, as e.g. [MgFe].