Stellar Metallicities and the Formation of the Galactic Bulge

Abstract

In order to probe the formation history of the Galactic bulge, we compare the metal abundances of K giant bulge stars with a large number of star formation histories which are generated by a model of chemical enrichment. A Kolmogorov-Smirnov test rules out infall timescales longer than 1 Gyr at the 90 per cent confidence level, with preferred values being shorter than ∼ 0.5 Gyr. This result favours bulge formation scenarios based on a single massive burst, as opposed to the weaker and more extended star formation histories predicted by stellar accretion and merger-induced bursts. Accurate estimates of [Mg/Fe] over a large sample of bulge giants will unambiguously constrain both the infall as well as the star formation timescales.