Yue Hu (Institute for Advanced Study) - Polarized Dust and Synchrotron Emission: The Magnetized ISM as CMB Foreground

Polarized Galactic emission — thermal dust and synchrotron radiation — is the primary obstacle for detecting primordial CMB B-mode polarization, yet it also encodes rich information about magnetic fields and turbulence in the interstellar medium. In this talk, I present a physically motivated view of both foreground components. For thermal dust, I show using high-resolution 3D MHD simulations of the turbulent multiphase ISM that the warm, unstable, and cold neutral media contribute distinctly to polarization power spectra and the EE/BB power ratio — with the unstable neutral medium emerging as the likely dominant foreground contributor consistent with Planck observations. For synchrotron emission, I present preliminary results from MHD-PIC simulations that self-consistently capture cosmic ray dynamics and their polarized emission. Finally, I discuss how  artificial intelligence approaches can reconstruct the 3D Galactic magnetic field from spectroscopic observations, offering a path toward more accurate foreground modeling for next-generation CMB experiments.

The FCAD Astronomy Seminars cover a wide range of topics with speakers of all career levels, from graduate students and postdocs to faculty. The seminars take place on Wednesdays from 12-1 PM in LGRT 533. All members of the FCAD community are welcome to attend.