Abstract details

The combination of huge databases of galaxy spectra and evolutionary synthesis models offers promising prospects for the study of galactic histories. The synthesis problem consists of going from an integrated spectrum to the stellar population mixture which produces it. This classical problem has been tackled by a variety of techniques, differing both in mathematical aspects and astrophysical ingreedients. Recently it has become possible to fit the full optical spectrum of a galaxy by combining state-of-the-art models for stellar ppopulations of various ages and metallicities. This review describes this spectral synthesis technique, focusing on its application for late-type (star-forming) galaxies. We discuss how sensitive the results are to ingredients in the fits and present some systematic problems identified in the observed minus model spectra of over 350k SDSS galaxies. Notwithstanding such problems, experience has taught us that, besides producing super fits to the data, this method produces astrophysically sound results, such as correlations between stellar and nebular extinctions and metallicities, the mass-metallicity relation, etc. We also compare emission-line and starlight based diagnostics of the recent star-formation history.