Investigating the Central Density Profile of Dark Matter Halos Using Mergers

The dark matter halos of galaxies and galaxy clusters form by a “bottom-up” process in which smaller objects merge to form larger ones. In recent years simulations have suggested that these dark matter halos possess a universal density profile that is independent of mass, cosmological parameters, and formation history. To investigate the cause of this profile, we perform a series of “controlled experiments” merging dark matter halos of different sizes, density profiles and orientations. We then fit the resulting density profile to various functions representing candidates for universal density profiles.