Cosmology Seminar: Jack Morrice
Jack Morrice is a post-doctoral fellow at the University of Cape Town
Glowing Cosmic Surfaces
Cold collision-less dark matter streams form caustics---giant 2D surfaces in 3D space of near infinite density---in as they fall into gravitational potential wells. These caustics are huge: similar in size to the halos, and very thin: typical thicknesses of 10^-8 times the halo size, but with densities around 10^5 times the halo mean (Hogan, 2001). If dark matter annihilates, and the annihilation cross section depends on the density, then we expect the bulk of annihilation signals to come from these caustics. These surfaces would `glow` at frequencies dependent on the type of dark matter particle. This talk is about our (Miguel and Jack)'s preliminary attempts to understand the shapes and multiplicity of these surfaces in the early stages of collapse.