Joint Astrophysics Colloquium

Stellar Feedback in Dwarf Galaxy Formation and the Structure of Dark Matter Halos

James Wadsley

Department of Physics & Astronomy
McMaster University

Dwarf galaxies pose significant challenges for cosmological models. In particular, N-body models predict a central dark matter distribution that is cuspy (highly concentrated at the center). In contrast, observations indicate a roughly constant central density core. Energetic feedback from supernova explosions and stellar winds is already assumed to be a major factor shaping the evolution of dwarf galaxies and we have shown that it can strongly affect the dark matter as well. We present detailed cosmological simulations with sufficient resolution to directly model the impact of stellar feedback on the observable properties of dwarf galaxies. Feedback drives large-scale, bulk motions of the interstellar gas resulting in significant gravitational potential fluctuations and a consequent reduction in the central matter density, bringing the theoretical predictions in agreement with observations.

Our results have implications for the formation of globular clusters and the distribution of stars in dwarf galaxies.