non-integrable galaxies

As my loyal reader knows, I am strongly against modeling non-integrable systems with integrable potentials. And guess what: No galaxy in any kind of realistic dark-matter mass distribution could ever have an integrable potential! During a meeting today (and yesterday also, which perhaps doesn't count according to the implicit parts of The Rules), Fadely, Foreman-Mackey, and I talked about how to generalize things like Schwarzschild modeling to non-integrable potentials and proper probabilistic inference. Glenn van de Ven (MPIA) does these things for a living, so we wrote him email and he sent back some great suggestions for how to proceed. Now the question is: Should we implement something, even if it means reinventing a few wheels? It didn't take us long to decide: Yes!. Ah, Camp Hogg prefers engineering to science these days. One set of ideas I am excited about is how to write down a prior over phase-space distribution functions when you don't have an integrable-potential action–angle language in which to write it. I love that hairball of problems.