Extreme value statistics of CMB lensing deflection angles
  The smaller the angular scales on which the anisotropies of the cosmic
microwave background (CMB) are probed the more important their distortion due
to gravitational lensing becomes. Here we investigate the maxima and minima of
the CMB lensing deflection field using general extreme value statistics. Since
general extreme value statistics applies to uncorrelated data in first place we
consider appropriately low-pass filtered deflection maps. Besides the
suppression of correlations filtering is required for another reason: The
lensing field itself is not directly observable but needs to be (statistically)
reconstructed from the lensed CMB by means of a quadratic estimator. This
reconstruction, though, is noise dominated and therefore requires smoothing,
too. In idealized Gaussian realizations as well as in realistically
reconstructed data we find that both maxima and minima of the deflection angle
components follow consistently a general extreme value distribution of
Weibull-type. However, its shape, location and scale parameters vary
significantly between different realizations. The statistics' potential power
to constrain cosmological models appears therefore rather limited.
