TITLE:
Gravitational lensing as a contaminant of the gravity wave signal in CMB.
AUTHOR(S):
Uros Seljak and Christopher M. Hirata (Princeton University)
DATE:
2003 Oct 06 (arXiv, v1, posted);
2003 Oct 06 (Phys. Rev. D, submitted);
2003 Nov 18 (revised);
2003 Nov 21 (Phys. Rev. D, accepted);
2004 Feb 27 (Phys. Rev. D, published).
AVAILABILITY:
arXiv
astro-ph/0310163 (free); APS (requires subscription).
PUBLICATION INFORMATION: Physical Review D, 69, 043005 (2004), 6 pages
ABSTRACT:
Gravity waves (GW) in the early universe generate B-type polarization in the cosmic microwave background (CMB), which can be used as a
direct way to measure the energy scale of inflation. Gravitational lensing contaminates the GW signal by converting the dominant E
polarization into B polarization. By reconstructing the lensing potential from CMB itself one can decontaminate the B mode induced by
lensing. We present results of numerical simulations of B mode delensing using quadratic and iterative maximum-likelihood lensing
reconstruction methods as a function of detector noise and beam. In our simulations we find the quadratic method can reduce the lensing
B noise power by up to a factor of 7, close to the no noise limit. In contrast, the iterative method shows significant improvements even
at the lowest noise levels we tested. We demonstrate explicitly that with this method at least a factor of 40 noise power reduction in
lensing induced B power is possible, suggesting that T/S=10-6 may be achievable in the absence of sky cuts, foregrounds, and
instrumental systematics. While we do not find any fundamental lower limit due to lensing, we find that for high-sensitivity detectors
residual lensing noise dominates over the detector noise.
ADS BIBLIOGRAPHIC CODE:
2004PhRvD..69d3005S
COMMENTS: