Cross-correlations at all scales: correlating optical and CMB surveys to probe physics at very large and very small scales

CMB surveys are correlated with optical imaging surveys as a result of secondary anisotropies and foreground emission. In this talk, I will illustrate with two examples how we can exploit these correlations to probe physics across a huge range of length scales. First, by cross-correlating galaxy surveys with measurements of gravitational lensing of the CMB, we can tighten cosmological constraints from galaxy surveys and improve their robustness to systematic errors. Second, and somewhat surprisingly, correlations between optical surveys and CMB surveys can provide insight into the outskirts of planetary systems, potentially enabling the first direct detection of Oort clouds and improving our chances of detecting Planet 9.

Speaker: Eric Baxter, Penn State Univ.