# SLAC-2017:Foregrounds

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## Contents

## Foregrounds and simulations

Post talks here:

- r -- Lloyd Knox slides
- TT/TE/EE -- Erminia Calabrese slides
- Lensing -- Blake Sherwin slides
- Clusters -- Colin Hill slides

## Notes from session

### r: Lloyd Knox

- From Science Book, expect two distinct surveys for r: one at low resolution with many frequencies (for tensors), one with high resolution but fewer frequencies (for delensing)
- Defined a staged series of data challenges. Simulated maps exist at NERSC, analysis of first data challenge is underway. Start simple, update survey and signals in later rounds.
- Science Book used Fisher forecast to allocate sensitivity between eight frequency bands for low-res survey plus high-res survey.
- Important question: Do we need additional frequencies below 30 GHz?
- Survey definitions:
- X=1: Science Book case with fsky=3% (check codes to confirm that we can reproduce Science Book results)
- X=2: Updated set of bandpasses, multiple values of fsky.
- X=3: Include both low-res and high-res surveys

- Signal definitions:
- Y=0: Lensed and partially-delensed CMB, Gaussian dust and synchrotron, no extragalactic foregrounds
- Y=1: PySM 'standard' model = Galactic foregrounds (non-Gaussian, spatially varying indices for sync/dust), no extragalactic foregrounds
- Y=2: PySM 'alternate' model
- Y>2: Ben Thorne and Brandon Hensley working to add Hensley / Drain dust model, add extragalactic foregrounds consistent with CMB lensing (Alvarez/Battaglia/Bond)

### TT/TE/EE: Erminia Calabrese

- Study impact of CMB secondaries, Galactic and extragalactic foregrounds on science from small-scale T/E. Build a covariance matrix including foreground uncertainty.
- Use templates and nuisance parameters for tSZ, kSZ, tSZxCIB, CIB-P, CIB-C, Radio-P, Cirrus in TT, Radio-P in TE/EE.
- Make simulations and multi-frequency covariance matrix. Repeat for different experiment configurations. Then analyze to solve for nuisance parameters, CMB, and eventually cosmological parameters.
- Some constraints on secondary / Galactic / extragalactic nuisance parameters are orders of magnitude better than current limits. Will these models hold up at that precision?
- Five frequencies vs three improves secondary/foreground constraints, but doesn't impact damping tail science (Neff). TE is most constraining spectrum.
- No systematics currently included.

### Lensing: Blake Sherwin

### Clusters: Colin Hill

## Action items/Next steps

Summarize action items here