Iterative curved sky s06b nofg lensing templates

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Julien Carron, April 10 2020

This pages describes the 100 iterative (maximum a posteriori, 'MAP') lensing map built from the s06b simulations without foreground, and the associated lensing templates.

The CMB likelihood model used to build the maps include:

  • Curved-sky geometry
  • An inhomogeneous noise model built from the hit map /project/projectdirs/cmbs4/expt_xx/06b/rhits/n2048.fits together with the empirically estimated central noise value
  • Exact deprojection of all B-modes from 2 to 200, to ensure these modes are not used to build the lensing template
  • Used are E-modes from 2 to 3000 and B-modes from 200 to 3000
  • The same mean-field is used for each iteration

The approximation to the mean-field leaves a residual sometimes visible near the edges of the patch. This is however restricted to low lensing multipoles, and does not affect the B-template quality.

A typical cross-correlation to the input lensing looks like this (calculated in a central region of 900 sq. deg. within), where the L-modes relevant to the B-power are centred on L~500. The correlation there goes from ~85% to ~96%

        Cs MAP rho.pdf

The B-templates are built remapping the estimated unlensed E-mode

Across the central 900 sq. deg. region, I estimate the residual B-power after template substraction to be about 0.1 (for something close to 0.3 for the QE, the starting point)

        Cs resAL.png

Obviously the quality of the tracer and template degrades closer to the edges