# Difference between revisions of "MapBasedR"

David.Alonso (talk | contribs) |
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* Assuming no delensing: <math>\sigma(r)=1.6\times10^{-3}</math> | * Assuming no delensing: <math>\sigma(r)=1.6\times10^{-3}</math> | ||

* Assuming a 0.25 delensing factor: <math>\sigma(r)=0.84\times10^{-3}</math> | * Assuming a 0.25 delensing factor: <math>\sigma(r)=0.84\times10^{-3}</math> | ||

+ | These number roughly agree with Victor's forecast (<math>\sigma(r)=0.95\times10^{-3}</math>), considering our potentially different assumptions about noise power spectra and delensing efficiency. | ||

== Simulations == | == Simulations == |

## Revision as of 17:32, 18 May 2016

## Summary

We checked the case in Victor's forecasts using our map-based code on PySM simulations. Bullet-point results (details below):

- Assuming no delensing:
- Assuming a 0.25 delensing factor:

These number roughly agree with Victor's forecast (), considering our potentially different assumptions about noise power spectra and delensing efficiency.

## Simulations

We used PySM to generate full-sky simulations including:

- Power-law synchrotron (spatially-varying spectral index).
- Single-component thermal dust (spatially-varying temperature and spectral index).
- , partially de-lensed CMB.
- Noise levels compatible with Victor's case.

The simulations are cut using a map defined by selecting the cleanest 4000 sq-deg of the sky in polarization.

## Foreground removal

We run a map-based bayesian foreground-removal code on the simulations. The code samples the fully-resolved amplitudes of the three different components as well as spectral parameters ( and ). The latter are assumed constant on larger pixels, with HEALPix resolution (corresponding to ~4 deg). Fig. below shows the B-mode map at 145 MHz (left) and the mean CMB-only B-mode map output by the code (right).

## Estimating r

We compute the B-mode power spectrum for each simulation and fit a primordial + lensing template with amplitudes for both components (the first one being ). For this we only use multipoles . See result below for the no-delensing and 0.25-delensing cases.