SNe-Ia and the Formation History of Early-Type Galaxies

Abstract

Abundance ratios such as [Mg/Fe] are very powerful tracers of the past star formation histories of galaxies. The different contribution of Mg and Fe from supernovae of types Ia and II and their remarkably different onset timescales make [Mg/Fe] a useful tool to determine the duration of the star formation burst in early-type systems. We present a preliminary analysis of [Mg/Fe] radial gradients from the sample of Trager et al. The correlation found with galaxy mass suggests different dynamical formation scenarios between high- and low-mass ellipticals, favouring inside-out formation in low-mass systems versus an outside-in process in massive elliptical galaxies.