The Atacama Cosmology Telescope: DR6 Power Spectrum Foreground Model and Validation

Understand

We discuss the model of astrophysical emission at millimeter wavelengths used to characterize foregrounds in the multi-frequency power spectra of the Atacama Cosmology Telescope (ACT) Data Release 6 (DR6), expanding on Louis et al.

• (2025).
• We detail several tests to validate the capability of the DR6 parametric foreground model to describe current observations and complex simulations, and show that cosmological parameter constraints are robust against model extensions and variations.
• We demonstrate consistency of the model with pre-DR6 ACT data and observations from Planck and the South Pole Telescope.