momentum-driven winds, enfastening stellar models

At Galaxy Coffee, Jonathan Stern (MPIA) showed an analysis of quasar momentum-driven winds in the context of AGN feedback for galaxy evolution. He finds that the quasar radiation is not sufficient to drive the wind. In the discussion of the point Joachim Bestenlehner (MPIA) pointed out that Wolf–Rayet stars can have momentum-driven winds that exceed the naive radiation pressure L/c by a factor of five-ish. It relates to the fact that there are multiple scatterings of the radiation. Andrea Macció's (MPIA but soon NYU-AD) showed some nice work on simulations of small galaxies that are infalling in to the halos of larger galaxies.

Mike O'Neil came down to HD for two days (from Frankfurt) and we spent part of the afternoon understanding how to run and interpret PICO, which computes CMB power spectra. We started towards converting its output (which is in "ell" space) into a real-space covariance function. When we left work, O'Neil was looking at recurrence relations for Legendre polynomials!

We took advantage of O'Neil's presence to have a discussion with various MPIAers about interpolating grids of models (so that you can have a model defined everywhere in parameter space, but only compute it in full at a sparse set of points). He had various extremely useful points of advice. However, his reaction to the problem of interpolating 1-D LTE spectral models was not “do this kind of interpolation” but rather “I bet we can make the models run much, much, much faster!” So we downloaded the original Kurucz model paper [warning: huge PDF file] and began exegesis.

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