Milky Way archaeology and the dynamical signatures of merges

PhD ceremony: Mr. F.A. Gomez, 13.15 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: Milky Way archaeology and the dynamical signatures of merges

Promotor(s): prof. A. Helmi

Faculty: Mathematics and Natural Sciences

Under the current cosmological paradigm galaxies like our own Milky Way are formed bottom-up, through mergers and accretion of smaller objects that come together due to their gravitational attraction. If this paradigm is correct a vast amount of fossil remnants from the disruption of the accreted galaxies should be present in the different components of the Milky Way, such as its halo or thick disc. The quantification and the characterisation of these debris therefore provide crucial tests of this paradigm which, moreover, would allow us to establish the assembly history of our Galaxy.

In this thesis numerical and analytical methods have been used to characterise the dynamical signatures as well as the time evolution of debris associated with accretion events. Simulations at different levels of sophistication have been performed to study the impact of different physical mechanisms on the final distribution of debris in Galactic phase-space (Chapter 4 & 5). New methods and techniques have been developed to identify fossil signatures of accreted galaxies (Chapter 3), as well as to characterize how much of this history may be recovered with the advent of the European Space Agency astrometric satellite Gaia (Chapter 4). The problem of the very rapid initial divergence of nearby orbits observed in N-body simulations of fully integrable potentials has also been revisited in this work (Chapter 2).