Ringberg, day 4

Today was almost all Milky-Way rotation-curve work, all day. Eilers (MPIA) and I worked through a checklist of things we need to figure out, and some of them made the project clearer, and some much less clear. In order to model the rotation curve with a set of tracers that are phase-mixed but not on circular orbits, we need a model for the asymmetric drift. This model is fundamentally a Jeans model, for which we need to know various second moments of the velocity field, and some derivatives of density and velocity dispersion with respect to radius. The second moments are (relatively) easy to measure, but without a selection function it is hard to get the derivatives of the density field!

For now, we decided to get our density models from the literature, if we can. That doesn't look super-hopeful. But I'm still hoping!

Other work included conversations with Bedell (Flatiron) about how the regularization we are using in wobble to control spectral model complexity doesn't seem to want to be the same in different parts of the stellar spectrum (which are differently complex!); with Lauer (NOAO) about using PCA to build data-driven models of nuisances; and with Anderson (Flatiron) about using RR Lyrae stars from PanSTARRS to characterize (and also find new) halo substructures.

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