Reverse engineering the Milky Way

Understand

The ages, metallicities, alpha-elements and integrals of motion of globular clusters (GCs) accreted by the Milky Way from disrupted satellites remain largely unchanged over time.

• Here we have used these conserved properties in combination to assign 76 GCs to 5 progenitor satellite galaxies -- one of which we dub the Koala dwarf galaxy.
• We fit a leaky-box chemical enrichment model to the age-metallicity distribution of GCs, deriving the effective yield and the formation epoch of each satellite.
• Based on scaling relations of GC counts we estimate the original halo mass, stellar mass and mean metallicity of each satellite.