Sep 09, 2021 - Smoothed kappa maps
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Dick suggested that our problems with sensitivity to places where kappa is close to one and magnification diverges can be solved by smoothing the kappa maps. A natural first guess for the smoothing scale is an effective radius of the pixel. It is given by
[math]\displaystyle{ \pi \theta^2 = \frac{4\pi}{N_{pix}} }[/math]
and evaluates to
[math]\displaystyle{ \theta = (\sqrt{3}N_{side})^{-1} . }[/math]
Using the healpy smoothing routine with [math]\displaystyle{ \sigma = \theta }[/math], we pre-process the maps before lensing.
As visible from histograms, it helps to cure the tails:
Just for illustration we show what the smoothing does to the kappa map (shell 17):
