Reverse engineering the Milky Way
  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. The total stellar mass of the 5 accreted satellites contributed
around 10$^{9}$ M$_{\odot}$ in stars to the growth of the Milky Way but over
50\% of the Milky Way's GC system. The 5 satellites formed at very early times
and were likely accreted 8--11 Gyr ago, indicating rapid growth for the Milky
Way in its early evolution. We suggest that at least 3 satellites were
originally nucleated, with the remnant nucleus now a GC of the Milky Way.
Eleven GCs are also identified as having formed ex-situ but could not be
assigned to a single progenitor satellite.
