Reconstructing the Galactic merger history with machine learning

Just like archaeologists can trace the migration and assimilation of people in past societies, astronomers can reconstruct the assembly history of the Galaxy that we live in. In standard galaxy formation theory, galaxies like our Milky Way formed through the hierarchical merging of many smaller galaxies. According to this picture, some of the stars and star clusters in our Galaxy were not originally born here, but are "immigrants" that were brought into the Milky Way when their parent galaxy entered. Galactic archaeologists are developing techniques to trace back the origin of these galactic immigrants and reconstruct properties of the accreted galaxies. One avenue is through the stars that were left behind in a stream (see this Astrobite), but today's authors study where the star clusters in our galaxy come from.