Simons Observatory: Assessing and Modeling Foreground Complexity in CMB Analyses

The cosmic microwave background (CMB) polarization is a powerful probe of the physics of the early universe. The Simons Observatory is beginning to deliver high-sensitivity, multi-frequency data that will enable refined studies of Galactic foregrounds and their influence on cosmological inference. We examined the impact of spatial and spectral complexity in polarized dust emission on the power-spectrum-based analysis. Using realistic simulations, we identified that the scale-dependent spectral energy distribution can bias cosmological parameter estimation and outlined promising directions for improvement to enhance robustness. Building on these findings, we highlight ongoing efforts toward extending power-spectral approaches to better characterize foreground complexity in upcoming CMB data.