Speaker
Description
One of the most persistent small-scale challenges to the LCDM paradigm is the striking structural diversity of dwarf galaxies. Cosmological simulations struggle in reproducing the full range of galaxy size or the inner dark-matter distribution as inferred from kinematics observations. While there have been efforts resorting to fine-tuning baryonic feedback and environmental effects, simple modifications on the dark sector may provide a clean solution, via making the dark matter self-interacting. We develop a simple analytical procedure for computing the density profile of self-interacting dark matter (SIDM) halos, incorporating gravitational influence of inhabitant galaxies and show that the model reproduces cosmological SIDM simulation results remarkably well. We show that the halo response to baryons is more diverse in SIDM than in CDM, a desirable feature in the context of the structural diversity problem. Using this new model, we discuss constraining the SIDM cross section using observations of dwarf galaxies and satellite galaxies. Finally, we show preliminary results towards developing a full semi-analytical frame work for SIDM satellite evolution, incorporating dark ram-pressure and facilitation of gravothermal core-collapse by tidal truncation.
