2 May 2013

Speaker: pH lecture: Matthew Walker (CfA)

Title:Galactic Dynamics and the Nature of Dark Matter

Abstract: The motions of stars can tell us about the nature of particles. I will translate the stellar kinematics observed in the nearest, smallest and `darkest' galaxies into a test of the standard hypothesis that dark matter consists of `cold' and `collisionless' (i.e., weakly interacting) particles. The feasibility of this simple model now seems to require that baryon-driven processes (e.g., energetic feedback from supernova explosions) alter the internal structure of galactic dark matter halos systematically with respect to predictions derived from cosmological N-body simulations. I will identify future work that can tell definitively whether such reconciliation is energetically feasible or whether the dark matter model ultimately requires additional complexity.