Inhomogeneous halo collapse and the globular cluster metallicity gradient.

摘要

Globular cluster systems hold vital information on the formation and early evolution of galaxies. In particular, any correlation between kinematics and composition might allow us to probe the most active periods of galactic chemo-dynamics (GCD). Using the detailed observations of the Galactic globular cluster system, we study GCD of the Galactic halo. Assuming that the sub-class of halo globulars traces the star formation history of the halo, we investigate the chemical evolution of a collapsing, centrally condensed proto-galaxy. The absence of a strong radial metallicity gradient is used to test inhomogeneous models. We find that violent relaxation and supernova heating wash out the metallicity gradient established during the collapse. Following cluster orbits during collapse, when the potential changes rapidly, and in a static potential thereafter, we find a very small present-day metallcity gradient, consistent with the observations.