BeyondPlanck lifts veil after veil on the early universe

In the hunt for the fundamental truths about our universe, we must look deep into the polarized astrophysical sky. This is because the polarized cosmic microwave background (CMB), the faint signal carrying the secrets of the very early universe, is obscured by layers of light from different astrophysical origins. To peel off these layers, and get a crystal clear view, cosmologists in the BeyondPlanck collaboration decompose and characterize these signals, which is called foregrounds, using complex mathematical models. This means getting to know each of the foregrounds, such as light from vibrating dust particles, or that of electrons interacting with the Galactic magnetic field at relativistic speeds, down to the smallest details. In doing so, cosmologists learn important new information about our own galaxy, and provide valuable insights for several branches of cosmology and astrophysics!

The process of foreground characterization is by no means an easy task, and more often than not, the observing instrument doesn’t play on the same team. Furthermore, the interplay between the instrument systematics and foregrounds further complicates the process. That is why the BeyondPlanck team has developed a radical new approach which corrects for any instrumental defects, while at the same time estimates the foreground contamination using a combination Bayesian statistic and lots of computing power. The result is a showcase of a revolutionary approach presenting the polarized sky emission using never before combined data sets!