Brandon Hensley, Princeton, "New Perspectives on Polarized Dust Foregrounds for CMB Science"
Polarized dust emission from our Galaxy must be mitigated at the percent level (or better) to detect a B-mode signature from primordial gravitational waves in the Cosmic Microwave Background. In this talk, I will present new developments from a dust/ISM physics perspective that will help us achieve these goals. First, I will propose a new physical model of interstellar dust that, breaking with four decades of dust modeling, posits that dust exists primarily as a single, homogenous species we call "astrodust." Implications for dust foregrounds will be highlighted. Next, I will discuss the remarkable ability of HI emission to not only trace the observed dust polarization with high fidelity, but also to extend this mapping to three dimensions. Using 3D realizations of the Galactic ISM from both HI observations and magnetohydrodynamic simulations, I will make predictions for the level of frequency decorrelation in the dust BB spectrum. Finally, I will present evidence that dust frequency decorrelation is already detectable in the Planck data if one simply knows where to look.