Sarah Martell (UNSW)

Sarah Martell Colloquium: Globular clusters and halo assembly

Marsfield

Abstract

Hierarchical accretion models for galaxy formation predict that the majority
of stars in the halo of a spiral galaxy should have formed within dwarf
galaxies that were later accreted by the larger galaxy. In 2010, we used a
rough chemical tagging approach to identify stars in the Milky Way halo that
had likely formed in globular clusters, using the light-element abundance anomalies
that are well-studied in Galactic globular clusters. This was the first
identification of this population of halo stars that formed in situ, and
subsequent studies have confirmed our initial result. Ideally one would use
this chemically taggable population, which comprises around 2.5 per cent of the halo,
to explore the importance of in situ star formation in halo assembly.
However, the interpretation is strongly dependent on models for globular cluster
formation, mass loss, and dissolution. I will present a new search for
globular cluster migrants in the Galactic halo in SDSS-III APOGEE survey
data, and discuss the interpretation of this population in the light of
recent theoretical work on globular cluster formation that is upending
many previous assumptions.