Galac­tic archae­ol­ogy uses stars as fossils to better under­stand the evolu­tion of galax­ies, such as the Milky Way. Cosmo­log­i­cal simula­tions suggest that galax­ies enlarge partly by swallow­ing dwarf galax­ies. In this project, RR Lyrae stars are studied to look for remnants of past mergers that have contributed to the Milky Way's Formation.

Galac­tic archae­ol­ogy uses stars as fossils to study the evolu­tion­ary history of galax­ies like our own Milky Way. Cosmo­log­i­cal simula­tions suggest that larger galax­ies were partially formed by accret­ing smaller dwarf galax­ies. Such merger events should leave observ­able signa­tures in the form of star streams, but empir­i­cal constraints on the times, numbers, and impor­tance of such mergers are still missing.

This doctoral project super­vised by Hector Fellow Eva Grebel aims at galac­tic archae­ol­ogy using variable stars as tracers. These stars show a strictly periodic change of their luminos­ity and uniquely suited as tracers of distances, ages, and chemi­cal compo­si­tions. In recent years, many sky surveys were carried out that identi­fied and monitored large numbers of these variable stars. In this project, these surveys are exploited to search for remnants of past mergers that contributed to the build-up of the Milky Way and to explore their proper­ties, but also to charac­ter­ize native Galac­tic stellar populations.

One of the corner­stones of this project is the Gaia satel­lite of the European Space Agency. Gaia will, for the first time, provide a six-dimen­sional map of our galaxy with proper motions and radial veloc­i­ties for millions of stars. In combi­na­tion with the ground-based time-domain surveys, these data will allow us to study the assem­bly history of our galaxy in great detail and also to explore surviv­ing galac­tic build­ing blocks, i.e., neigh­bor­ing dwarf galaxies.