| Speaker: | Gerhard Hensler (University of Vienna/NAOJ) |
|---|---|
| Title: | The early evolution of the Milky Way's satellite system in CDM cosmology |
| Date (JST): | Thu, May 14, 2015, 13:30 - 14:30 |
| Place: | Seminar Room A |
| Abstract: |
The system of dwarf galaxies (DGs) around the Milky Way (MWG) belongs to the most poorly understood astronomical object and serves as the most challenging target in extragalactic astrophysics for various reasons: At first, because in Cold Dark Matter (CDM) cosmology DM subhalos and with them DGs are expected to form first, and because only local DGs can be observed down to the faintest end, the MWG satellites provide the ideal test bed for tracing back galaxy evolution over cosmic time. Secondly, satellite galaxies are required from CDM cosmology to build-up the mature galaxy by accretion. This still at present observable mass assembly of gas and stars by the MWG should have left over kinematic and chemical witnesses. At third, a huge number of subhalos is expected to surround our MWG but the observed low number of satellites around the MWG (and also the Andromeda galaxy) and their concentration to a disk-of-satellites put strong constraints on their formation and evolution scenario. And finally, without the claim of completeness, their mostly huge DM mass fractions must be raised. Since the observational facts lead to problems for a coherent picture of the MWG satellite system, a vast number numerical simulations have been undertaken for a better understanding of the evolution of satellites and the host MWG itself. This talk will critically review these efforts and present new simulations of the evolution of the satellite system of a MWG-type galaxy taken from cosmological simulations. Including star formation and the chemical and energetic stellar feedback, these models demonstrated how the chemo-dynamical evolution of the satellite system are affected by simple gas loss due to ram-pressure stripping and galactic winds, but also by their merging and by tidal stripping. This allows studying the early evolution of the MWG halo and its satellite galaxies. |
