Fisher Forecasts for the Simons Observatory and Desi and an Implementation of the Polarized Two-Messenger-Fields Method

We performed forecasts of the uncertainty with which future surveys will measure the cosmological parameters of the non-flat ΛCDM model, extended to include the sum of neutrino masses Σν, and the effective number of relativistic species N[subscript eff], with the Fisher matrix formalism. The surveys we studied are Planck, DESI, and the Simons Observatory (SO). We considered several different scenarios and datasets, such as two different sensitivity levels for SO, including and excluding galaxy-weak lensing cross-correlations, three different multipole cut-offs for galaxy and weak lensing data, and the impact of the widely used Limber approximation. For our nominal case, we find σN[subscript eff] = 0.0836, twice as good as the tightest constraints today. We also find σΣν = 43.4 meV, a much better constraint than today, but still not enough to determine the neutrino hierarchy with better than ~0.9σ confidence.\\ \newline We implemented the Two-Messenger-Fields method (2MF), a novel technique for filtering CMB data in cases of complicated noise properties. The implementation can handle polarized data in two commonly used pixellizations, healpix and enmap. We applied the method to filter data from the Atacama Cosmology Telescope (ACT) Data Release 4 Season 15. The method successfully recovers a signal reconstruction in situations of low signal-to-noise ratio and correlated stripy noise. We will apply the method on the rest of the ACT data, and we will make the implementation publicly available.