Modeling the formation of dark-matter deficient galaxies

Recent observations reported a puzzling dearth of dark matter (DM) in a fraction of massive galaxies at high redshift and dwarf galaxies, contrary to the expectations of current simulations within the standard LCDM scenario. We propose to better understand the structural evolution of DM halos in response to drastic mass/energy changes and the gravitational interplay between the DM and the baryons, including outflows, mergers, and tidal effects. For this, we developed a novel analytic model, “CuspCore2”, providing a unified and accurate framework for following the violent relaxation of a halo perturbed by the above processes. Utilizing this framework, we worked out a scenario for DM-deficient cores in high-z massive galaxies via DM “heating” by dynamical friction on compact merging satellites followed by DM expansion in response to AGN-driven outflows. The same framework can generate DM-deficient dwarf galaxies via supernova feedback and tidal stripping. Finally, the universality of the violent relaxation process ensures broad applications of our CuspCore2 model in general galactic dynamic problems.