The Disk of Galaxies and the Diversity of Galaxy Formation
Prof. Xinghai Zhao
Dalton State University
The satellite systems of MilkyWay like galaxies offer us great tools to study the galaxy formation process in the cosmological context. The current observed anisotropic distribution of the satellites in such galaxy systems has been suggested to be inconsistent with the concordance ΛCDM cosmology model on the galactic scale if the observed satellites are random samples of the dark matter (DM) sub-halos that are nearly isotropically distributed around the central galaxy. We use high resolution hydrodynamical simulations of the formation and evolution of MilkyWay like galaxy systems to investigate the spatial distribution of the luminous satellites and DM sub-halos around the central galaxy. We find that the satellites and DMsub-halos are indeed anisotropically distributed with a direction roughly along the local DM filament. The observed alignment of the satellites in these systems is likely the result of the preferred accretion along the local DM filaments in the galaxy formation process. For the dynamical properties of the satellites, we find that the direction of the angular momentum of the whole satellite system is different from the normal direction of the fitted “disk of satellites” (DOS) and the normal direction of the velocity dispersion of the system. So the fitted DOS is not rotationally supported in this study. Future observations will test these aspects when more low luminosity satellites are detected.
Hosted by Prof. Mathews