TITLE:
Reconstruction of lensing from the cosmic microwave background polarization.
AUTHOR(S):
Christopher M. Hirata, Uros Seljak (Princeton University)
DATE:
2003 Jun 18 (Phys. Rev. D, submitted);
2003 Jun 18 (arXiv, posted, v1);
2003 Jul 27 (revised);
2003 Aug 20 (Phys. Rev. D, accepted);
2003 Aug 21 (arXiv, posted, v2);
2003 Oct 22 (Phys. Rev. D, published).
AVAILABILITY:
arXiv
astro-ph/0306354 (free); APS
(requires subscription).
PUBLICATION INFORMATION: Physical
Review D, 68, 083002 (2003), 23 pages
ABSTRACT:
Gravitational lensing of the cosmic microwave background (CMB) polarization field has been recognized as a potentially
valuable probe of the cosmological density field. We apply likelihood-based techniques to the problem of lensing of CMB
polarization and show that if the B-mode polarization is mapped, then likelihood-based techniques allow
significantly
better lensing reconstruction than is possible using the previous quadratic estimator approach. With this method the
ultimate limit to lensing reconstruction is not set by the lensed CMB power spectrum. Second-order corrections are known
to produce a curl component of the lensing deflection field that cannot be described by a potential; we show that this
does not significantly affect the reconstruction at noise levels greater than 0.25 microK arcmin.
The reduction of the
mean squared error in the lensing reconstruction relative to the quadratic method can be as much as a factor of two at
noise levels of 1.4 microK arcmin to a factor of ten at 0.25 microK arcmin, depending on the angular scale of interest.
ADS BIBLIOGRAPHIC CODE: 2003PhRvD..68h3002H
COMMENTS:
This is a follow-on to our previous article on lensing reconstruction using CMB temperature
anisotropies, which showed that for that case the quadratic estimation method is near-optimal (at least for lensing by
large scale structure). It turned out (and initially surprised us!) that the result for CMB polarization is
qualitatively different: if noise is low, one can improve substantially upon the quadratic estimator. The implications for
gravitational wave searches in the CMB were presented in a later article.