gradients in cosmological power, and EPRV

In the morning, Kate Storey-Fisher (NYU) dropped by to discuss our projects on finding anomalies in the large-scale structure. We discussed the use of mocks to build code that will serve as a pre-registration of hypotheses before we test them. We also looked at a few different kinds of anomalies for which we could easily search. One thing we came up with is a generalization of the real-space two-point function estimators currently used in large-scale structure into estimators not just of the correlation function, but also its gradient with respect to spatial position. That is, we could detect arbitrary generalizations of the hemispheric asymmetry seen in Planck but in a large-scale structure survey, and with any scale-dependence (or different gradients at different scales). Our estimator is related to the concept of marked correlation functions, I think.

Late in the day, Bedell (Flatiron), Montet (Chicago), and Foreman-Mackey (Flatiron) showed great progress on measuring RVs for stars in high-resolution spectroscopy. Their innovation is to simultaneously fit all velocities, a stellar spectrum, and a telluric spectrum, all data-driven. The method scales well (linearly with data size) and seems to suggest that we might beat the m/s barrier in measuring RVs. This hasn't been demonstrated, but the day ended with great hopes. We have been working on this model for weeks or months (depending on how you count) but today all the pieces came together. And it easily generalizes to include various kinds of variability.

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