Today I am on my third of five talks in five days, as part of my Hunstead Lectures at Sydney. I spoke about MCMC sampling. A lot of what I said was a subset of things we write in our recent manual on MCMC. At the end of the talk there was some nice discussion of detailed balance, with contributions from Tuthill (USyd) and Sharma (USyd).
At lunch I grilled asteroseismology guru Tim Bedding (USyd) about measuring the large frequency difference delta-nu in a stellar light curve. My position is that you ought to be able to do this without explicitly taking a Fourier Transform, but rather as some kind of mathematical operation on the data. That is, I am guessing that there is a very good and clever frequentist estimator for it. Bedding expressed the view that there already is such a thing, in that there are methods for automatically generating delta-nu values. They do take a Fourier Transform under the hood, but they are nonetheless good Frequentist estimators. But I want to work on sparser data, like Gaia and LSST light curves. I need to understand this all better. We also talked about how it is possible for a gastrophysics-y star to have oscillations with quality factors better than 105. Many stars do!
That's all highly relevant to the work of Simon Murphy (USyd), who finds binary stars by looking at phase drifts in highly coherent delta-Scuti star oscillations. He and I spent an Afternoon of hacking on models for one of his delta-Scuti stars, with the hopes of measuring the quality factor Q and also maybe exploring new and more information-preserving methods for finding the binary companions. This method of finding binaries has similar sensitivity to astrometric methods, which makes it very relevant to the binaries that Gaia will discover.
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