Testing the cold dark matter paradigm with dwarf galaxies and stellar streams in Gaia and LSST

The first evidence that galaxies contain large amount of invisible dark matter has been revealed more than 50 years ago. Since then we learned that dark matter is more than five times more abundant than ordinary matter in the universe and that it is one of the key drivers of galaxy evolution, as all the galaxies including the Milky Way are embedded inside large dark matter halos. However, we still do not know much about the nature of dark matter particles and their distribution in the Milky Way and other galaxies. Also while the current cosmological paradigm based on cold dark matter (Lambda CDM) is very successful in reproducing a vast range of observations, the predictions of this model on small scales remain very poorly tested.

The goal of my research is to use our galactic neighbourhood, such as dwarf galaxies, orbiting around the Milky Way and stellar streams (streams of stars produced by satellites tidally disrupted by the Milky Way) to test Lambda CDM and learn more about dark matter. In particular I plan to use data from the Gaia satellite and other large surveys of the sky such as LSST to find and characterize stellar streams. The search and analysis of stellar streams will help me understand the past history of the Milky Way formation. The modelling of positions and velocities of stellar streams will tell me about the distribution of mass inside our Galaxy and in particular the distribution of dark matter; the analysis of the stellar density distribution inside stellar streams will allow me to detect small gravitational perturbations produced by small dark matter halos.
I also plan to develop new methods to search for dwarf galaxies orbiting the Milky Way in the Gaia data. This should allow me to detect galaxies of even lower mass than before and located even closer to the Sun, thus
enabling studies of the dark matter at small scales and searches for dark matter annihilation signal. Finally, I also plan to tackle a problem that is extremely important for the searches of dwarf galaxies and stellar streams in large imaging surveys of the sky: star-galaxy separation. With many deep imaging surveys ongoing and LSST survey around the corner, our ability of separating faint stars from faint galaxies is becoming the main limiting factor for the studies of faint structures around the Milky Way.