ERIS

When galactic history is known

What do phylogenetic trees tell us about the merging history of the Milky Way? 

Building trees from stars living in the galactic halo might provide us with novel and interesting insights about the merging history of the Milky Way. We choose the galactic halo because its stellar content is made of stars of different origins that were accreted into the Milky Way. The problem with using real data is that it is not possible to know for sure which stars have ex-situ or in-situ origins. Therefore, we use simulated galaxies in a cosmological context.  Since we know exactly what is the history of each simulated galaxy, we can track back stellar particles in time along their merger trees , and assess the performance of our techniques to build phylogenetic trees. In the simulations, we can further explore different merging scenarios and diverse  star formation histories, and so understand better the impact of different formation scenarios on the overall trees.