Astronomy & Astrophysics Seminar: Core formation from outflow episodes induced by feedback

Abstract:

While cold dark matter numerical simulations predict steep, `cuspy' density profiles for dark matter halos, observations favor shallower `cores'. The introduction of baryons alleviates this discrepancy, notably as feedback-driven outflow episodes can expand the dark matter distribution. I will present two theoretical models for the response of a dissipationless spherical system to gas outflows, which could also be relevant to explain the formation of ultra diffuse galaxies. The first model considers a sudden removal of gas and divides the response of the system into an instantaneous change of potential at constant velocities followed by an energy-conserving relaxation. The second one assumes that stochastic density fluctuations induced by feedback deviate collisionless particles from their trajectories as in a diffusion process. Both models provide simple understandings of the formation of dark matter halo cores and ultra diffuse galaxies by supernova-driven outflows. 

Seminar Organizer: Dr. Omer Bromberg