Event Detail Information
Astrophysics Colloquium: Matthew Walker, Center for Astrophysics, Harvard University: "Galactic Dynamics and the Nature of Dark Matter"
I will explain how to use the motions of stars to learn about the nature of particles. More specifically, I will translate the stellar kinematics that I observe 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. This model escapes falsification only if 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 -- both observational and theoretical -- that I expect will tell definitively whether such reconciliation is energetically feasible or whether the dark matter model requires additional complexity.