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Large galaxies like the Milky Way form hierarchically, with smaller systems merging and accreting to form increasingly massive structures. Evidence for this process can be found all around us: spatially in the form of stellar streams and tidally disrupting satellites in the Galactic halo; dynamically as stellar overdensities in phase space within the Galactic disk; and chemically, in the form of abundance patterns distinct from those of typical stars which formed in situ within the Milky Way. I will briefly outline what we know - or at least, think we know - about the Milky Way’s assembly history, highlighting the work of two ongoing Australian-led spectroscopic surveys, GALAH and S5, in identifying and characterising discrete accretion events. Recent studies with GALAH data clearly show the importance of abundance patterns for detecting accreted structures within the Galaxy, while S5 results I will discuss include evidence for the influence of the LMC on halo stream orbits, an apparent orbital bias in the stellar streams observed, and comparisons with FIRE simulation predictions for detectable streams. I will conclude with a look at the prospects of new facilities such as LSST for driving major advances in our understanding of how galaxies like the Milky Way grow. |
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