Removal of Galactic foregrounds for the Simons Observatory primordial gravitational wave search

Understand

Upcoming observations from the Simons Observatory have been projected to constrain the tensor-to-scalar ratio, $r$, at the level of $\sigma(r)=$0.003.

• Here we describe one of the forecasting algorithms for the Simons Observatory in more detail, based on cleaning CMB polarization maps using a parametric model.
• We present a new code to perform this end-to-end forecast, and explore the assumptions in greater detail.
• If spatial uniformity of the spectral energy distribution of synchrotron radiation and thermal dust emission is assumed over the region planned for observations, covering almost a fifth of the sky, a bias of order 1--3$\sigma$ in $r$ is projected for foreground models consistent with current data.