At MPIA Galaxy Coffee, K. G. Lee (MPIA) and Jose Oñorbe (MPIA) gave talks about the intergalactic medium. Lee spoke about reconstruction of the density field, and Oñorbe spoke about reionization. The conversations continued into lunch, where I spoke with the research group of Joe Hennawi (MPIA) about various problems in inferring things about the intergalactic medium and quasar spectra in situations where (a) it is easy to simulate the data but (b) there is no explicit likelihood function. I advocated likelihood-free inference or ABC (as it is often called), plus adaptive sampling. We also discussed model selection, and I advocated cross-validation.
In the afternoon, Ness and I continued code review and made decisions for final runs of The Cannon for our red-giant masses and ages paper.