more gradients, combinatorics and inference

After making and sending radial abundance gradients (in the Milky Way) around to the APOGEE collaboration, I realized that I could just as easily do vertical gradients. I made and sent those today. The interesting things appear to be that alpha elements do not all track one another, and the gradient differences among them in the radial direction is different from that in the vertical direction. Interpretation is not trivial, however, because of radial migration and its attendant implications for variation in height distributions.

I started to code up the idea that Daniel Foreman-Mackey and I talked about earlier in the week: Making toy inference problems that have analytic Bayesian evidence integrals but combinatoric degeneracies (labeling degeneracies) among sets of parameters. I got started, and worked out some of my conceptual issues. Not all of them, though! A conversation with Alex Barnett (SCDA) helped immensely.

1 comment:

  1. Please forward any analytic examples you find, I'd love to DNest/RJObject them. I've had some weird sceptics who (mistakenly, IMO) think the combinatoric degeneracy needs special thought. It would be nice to make a simple demonstration showing otherwise (or, less plausibly, showing that I'm wrong).