The local group in CDM. Shapes and masses of dark halos

PhD ceremony: Mr. C.A. Vera Ciro, 11.00 uur, Academiegebouw, Broerstraat 5, Groningen

Disertation: The local group in CDM. Shapes and masses of dark halos

Promotor(s): prof. A. Helmi

Faculty: Mathematics and Natural Sciences

In this PhD-thesis we study the properties of dark matter halos assembled in the Lambda-Cold Dark Matter (Lambda-CDM) paradigm and its substructures.

The first part focuses on the geometry of the mass distribution of such objects. We find that the shapes of isolated Milky Way-like dark halos significantly deviate from the spherical symmetry and respond to the local environment, directly correlating with the way in which mass accretion takes place. The shape and orbital structure for the satellite structures inside these halos is also analyzed in detail. In general, these objects are rounder than their more massive hosts, and exhibit clear imprints of tidal disruption in both their geometrical shapes and internal orbital structure.

After this, we use the number of massive structures around the Milky Way to put constraints on the total mass of the Galactic dark matter halo. The properties of the mass distribution of the Milky Way dark matter halo are investigated further in the last chapter, where we use the stellar stream associated to the Sagittarius dwarf galaxy to constraint the shape of the Galactic potential. We put forward a new model that integrates our knowledge about the formation of the Galactic disk, the impact of satellite galaxies on measurements of the Galactic potential, and that is finally consistent with the Lambda-CDM paradigm.