Using Globular Clusters as Tracers of Galaxy Formation

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Galaxies grow through two channels: accretion of diffuse gas and dark matter via filaments and mergers with other galaxies. Mergers with other galaxies can be in the form of a major merger: where two galaxies of similar mass collide, potentially changing the morphological type of the galaxy. Minor mergers, however, are far more common, this is where a galaxy of lower mass is accreted onto a more massive galaxy.Signatures of both types of merger can be observed in the universe today. The minor merger events can leave their trace in the form of streams of stars which have been gravitationally stripped from the lower mass galaxy. There is evidence of this in our own galaxy in the form of the Sagittarius dwarf galaxy which is being tidally distorted by the Milky Way. It has been found that the properties of the globular clusters (GCs) which are spatially associated with this dwarf galaxy have a different chemical composition and potentially age than the rest of the Galactic GC population.Globular clusters (GCs) are a powerful tool for building up a picture of the formation of a galaxy: their spatial distribution and chemical composition reflect the merger and star formation histories of their host galaxy. However, previous work has mainly been observational in nature, leaving a gap in our theoretical understanding of GC populations and their formation. E-MOSAICS (MOdelling Star cluster system Assembly in Cosmological Simulations within EAGLE)- the first work to implement star cluster formation and evolution into hydrodynamical, cosmological simulations- will be used to trace a galaxy's GC system back through time to investigate where each GC was formed. This allows us to relate the properties of a GC system to various host galaxy properties and ultimately use a galaxy's GC system to build up a picture of its formation.