Polarization map of the CMB + galactic foregrounds at 140 GHz
Credit: Susanna Azzoni (Oxford)

Cosmology seminar: The hierarchical structure of galaxies in the Local Group

07 Feb 2023
Seminars and colloquia
Time
Venue
Beecroft Seminar Room
Denys Wilkinson Building, Department of Physics, University of Oxford, Keble Road, Oxford OX1 3RH
Speaker(s)

Isabel Santos-Santos (Durham University)

Seminar series
Cosmology
Knowledge of physics?
Yes, knowledge of physics required

Abstract:

The hierarchical nature of LCDM suggests that dark matter halos of all masses are successively surrounded by less massive ones. The Milky Way (MW) and its satellites are examples of this hierarchy, but it is expected that, on a smaller scale, dwarf galaxies should be surrounded by their own satellites as well. In this sense, the LMC (the MW’s most massive satellite, today at first infall) arises as a strong candidate to having its own satellite population and can be used to test CDM. In this talk I will address this “satellites-of-satellites” issue using predictions from Local Group cosmological simulations.
I will explain how the specific kinematic stage of the LMC, with its own satellites, is important in order to interpret MW data. I will also show how the abundance of faint satellites around dwarf galaxies is directly linked to the shape of the underlying stellar mass-halo mass relation. Finally, I will remark the importance of considering the existence of substructure beyond the nominal virial radius of halos (“backsplash” galaxies) to explain the puzzling observational data of some LG dwarfs. All these predictions have important implications to our understanding of how galaxy formation proceeds in the smallest DM halos, and may soon be tested with upcoming surveys.