Fossil stellar streams and their globular cluster populations in the
  E-MOSAICS simulations
  Stellar haloes encode a fossil record of a galaxy's accretion history,
generally in the form of structures of low surface brightness, such as stellar
streams. While their low surface brightness makes it challenging to determine
their age, metallicity, kinematics and spatial structure, the infalling
galaxies also deposit globular clusters (GCs) in the halo, which are bright and
therefore easier to observe and characterise. To understand how GCs associated
with stellar streams can be used to estimate the stellar mass and the infall
time of their parent galaxy, we examine a subset of 15 simulations of galaxies
and their star clusters from the E-MOSAICS project. E-MOSAICS is a suite of
hydrodynamical simulations incorporating a sub-grid model for GC formation and
evolution. We find that more massive accreted galaxies typically contribute
younger and more metal rich GCs. This lower age results from a more extended
cluster formation history in more massive galaxies. In addition, at fixed
stellar mass, galaxies that are accreted later host younger clusters, because
they can continue to form GCs without being subjected to environmental
influences for longer. This explains the large range of ages observed for
clusters associated with the Sagittarius dwarf galaxy in the halo of the Milky
Way compared to clusters which are thought to have formed in satellites
accreted early in the Milky Way's formation history. Using the ages of the GCs
associated with the Sagittarius dwarf, we estimate a virial radius crossing
lookback time (infall time) of $9.3 \pm 1.8 Gyr$.
