Interactions of Dark and Baryonic Matter in Dwarf Galaxies
thesisposted on 02.08.2012, 12:09 by David Ronald Cole
The ΛCDM model for structure formation in the universe has been successful on large scales, however there are outstanding problems on the scale of galaxies. In this thesis we study a number of processes where baryonic and dark matter (DM) interact on the scale of galaxies in order to provide a greater understanding of how such processes can explain observations. One significant issue for ΛCDM is the prediction of cusped density profiles for DM halos. In Chapter 2 we consider the infall of a massive baryonic clump into a dark-matter halo and demonstrate that the baryons need to transfer only a small fraction of their initial energy to the dark matter via dynamical friction to explain the discrepancy between predicted dark-matter density profiles and those inferred from observations. The observational evidence for density cores in local dwarf galaxies is still disputed. In Chapter 3 we consider what the existence of five globular clusters (GCs) tells us about the dynamical history of the Fornax dSph system and the implications for its density profile. We find that if Fornax has an extended dark matter core (as opposed to a density cusp) then its GCs remain close to their currently observed locations for long times. In Chapter 4 we study the effect of a Central Mass Concentration (CMC) on the development of a bar in a galactic disc with differing density profiles for its DM halo. We find the relative density of the DM halo affects the potency of the CMC in suppressing the growth of a bar.