Colin Hill (IAS) – "Fundamental Physics from the Foreground-Obscured Microwave Sky: Inflation, Neutrino Masses, and Beyond"

The cosmic microwave background (CMB) remains a key source from which to extract information about fundamental physics, due to its clean, well-understood origin and immense constraining power on many types of new physics. The next decade of CMB observations will yield answers to at least two fundamental questions: (1) did large-field inflation source the initial density perturbations in our universe? (2) what is the absolute mass scale of the neutrinos? In this talk, I will explain the routes by which these answers will be obtained. Both rely on highly precise measurements of the polarization of the CMB, which can be used to search for the signature of primordial gravitational waves (answering the first question) and to measure the growth of cosmic structure via gravitational lensing (answering the second question). Moreover, I will describe new methods with which to overcome the most significant challenge to this program: emission from non-primordial foreground sources. I will highlight the major role that the Simons Observatory and CMB-Stage IV experiments will play in these exciting developments. Finally, I will describe additional unique information about the distribution and properties of baryons and dark matter that these measurements will yield, providing crucial feedback for cosmological analyses with DESI and other large-scale structure surveys.