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Robust forecasts on fundamental physics from the foreground-obscured, gravitationally-lensed CMB polarization

Study based on

A web interface of the code is accessible on NERSC: The tool allows you to look at specific instrumental configurations (sensitivities, frequencies, bandpasses, FWHM), choose dust and synchrotron spectral indices, sky components, delensing options (CMBxCMB, CMBxCIB), marginalization for cosmological constraints.

I. Forecast on inflation:

These forecasts are based on the optimized experimental configurations provided by Victor Buza here. In summary, there are six configurations, assuming three values of (0.01, 0.05 and 0.1) and two values of (0 and 0.01). The experiment is broken down into a multi-frequency "degree-scale" effort aimed at cleaning foregrounds and a single-frequency (assumed 145 GHz, 1' FHWM) "arcmin-scale" effort aimed at delensing; both efforts are assumed to have access to a multipole range of . We combine all of these bands together and pass to our component-separation, delensing and Fisher formalism, assuming dust and synchrotron are present and using iterative CMB EBEB delensing (we can also provide constraints for no/CIB/LSS delensing). We perform the same procedure for Planck (we don't use the WMAP channels), and combine the two Fisher matrices together. We assume a simple CDM+ model, and constrain it using , , and information.

3.67 4.48 4.59
1.48 1.00 0.880

Clearly we have more optimistic results than Victor. This may be because we're using polarization noise levels rather than temperature; we also consider fewer foreground parameters than Victor does. There could also be differences in the way we're delensing. Essentially, we should discuss!

II. Forecast on other cosmological parameters

We derive here results which aim at being compared to Erminia’s forecasts: Some discrepancies might appear due to different assumptions, priors, polarized vs. total intensity sensitivity, etc.

We look at the variation of cosmological constraints (neutrino mass, Neff, running and curvature) as a function of polarized sensitivity or resolution. We combine the one-channel CMB-S4 with Planck and/or DESI BAO measurements.