The Stellar Mass Function in Globular Clusters

Abstract

Globular clusters in our own Milky Way formed at redshift z≃5 or more, when the physical conditions of the environment, such as pressure, density, temperature and chemical composition, were very different from those found in current star forming regions. The end product of this massive star formation is a stellar initial mass function (IMF) that holds the secret to the making of stars in the primeval universe. Over time, under the effects of stellar evolution and dynamical interactions, the stellar IMF of globular clusters has evolved to become what we can now accurately measure with the HST down to very small masses near the Hydrogen burning limit. But how does this present mass function compare with the original IMF and what can we learn from it about star formation at high redshift? I report here on the discovery of a surprising correlation between the shape of the current mass function of globular clusters and their central concentration, which suggests that our understanding of their dynamical evolution might not yet be complete.