CMB internal delensing with general optimal estimator for higherorder correlations
We present here a new method for delensing B modes of the cosmic microwave background (CMB) using a lensing potential reconstructed from the same realization of the CMB polarization (CMB internal delensing). The B mode delensing is required to improve sensitivity to primary B modes generated by, e.g., the inflationary gravitational waves, axionlike particles, modified gravity, primordial magnetic fields, and topological defects such as cosmic strings. However, the CMB internal delensing suffers from substantial biases due to correlations between observed CMB maps to be delensed and that used for reconstructing a lensing potential. Since the bias depends on realizations, we construct a realizationdependent (RD) estimator for correcting these biases by deriving a general optimal estimator for higherorder correlations. The RD method is less sensitive to simulation uncertainties. Compared to the previous ℓ splitting method, we find that the RD method corrects the biases without substantial degradation of the delensing efficiency.
 Authors:

^{[1]}
 Stanford Univ., CA (United States). Dept. of Physics; Stanford Univ., CA (United States). Kavli Inst. for Particle Astrophysics and Cosmology; SLAC National Accelerator Lab., Menlo Park, CA (United States)
 Publication Date:
 Grant/Contract Number:
 AC0276SF00515; AC0205CH11231
 Type:
 Accepted Manuscript
 Journal Name:
 Physical Review D
 Additional Journal Information:
 Journal Volume: 95; Journal Issue: 10; Journal ID: ISSN 24700010
 Publisher:
 American Physical Society (APS)
 Research Org:
 SLAC National Accelerator Lab., Menlo Park, CA (United States)
 Sponsoring Org:
 USDOE
 Country of Publication:
 United States
 Language:
 English
 Subject:
 79 ASTRONOMY AND ASTROPHYSICS; Gravitational lenses; Gravitational wave detection; cosmic microwave background; CMB
 OSTI Identifier:
 1369439
 Alternate Identifier(s):
 OSTI ID: 1372552
Namikawa, Toshiya. CMB internal delensing with general optimal estimator for higherorder correlations. United States: N. p.,
Web. doi:10.1103/PhysRevD.95.103514.
Namikawa, Toshiya. CMB internal delensing with general optimal estimator for higherorder correlations. United States. doi:10.1103/PhysRevD.95.103514.
Namikawa, Toshiya. 2017.
"CMB internal delensing with general optimal estimator for higherorder correlations". United States.
doi:10.1103/PhysRevD.95.103514. https://www.osti.gov/servlets/purl/1369439.
@article{osti_1369439,
title = {CMB internal delensing with general optimal estimator for higherorder correlations},
author = {Namikawa, Toshiya},
abstractNote = {We present here a new method for delensing B modes of the cosmic microwave background (CMB) using a lensing potential reconstructed from the same realization of the CMB polarization (CMB internal delensing). The B mode delensing is required to improve sensitivity to primary B modes generated by, e.g., the inflationary gravitational waves, axionlike particles, modified gravity, primordial magnetic fields, and topological defects such as cosmic strings. However, the CMB internal delensing suffers from substantial biases due to correlations between observed CMB maps to be delensed and that used for reconstructing a lensing potential. Since the bias depends on realizations, we construct a realizationdependent (RD) estimator for correcting these biases by deriving a general optimal estimator for higherorder correlations. The RD method is less sensitive to simulation uncertainties. Compared to the previous ℓ splitting method, we find that the RD method corrects the biases without substantial degradation of the delensing efficiency.},
doi = {10.1103/PhysRevD.95.103514},
journal = {Physical Review D},
number = 10,
volume = 95,
place = {United States},
year = {2017},
month = {5}
}