TY - JOUR
T1 - Internal delensing of cosmic microwave background acoustic peaks
AU - Sehgal, Neelima
AU - Madhavacheril, Mathew S.
AU - Sherwin, Blake
AU - Van Engelen, Alexander
N1 - Publisher Copyright:
© 2017 American Physical Society.
PY - 2017
Y1 - 2017
N2 - We present a method to delens the acoustic peaks of the cosmic microwave background (CMB) temperature and polarization power spectra internally, using lensing maps reconstructed from the CMB itself. We find that when delensing CMB acoustic peaks with a lensing potential map derived from the same CMB sky, a large bias arises in the delensed power spectrum. The cause of this bias is that the noise in the reconstructed potential map is derived from, and hence correlated with, the CMB map when delensing. This bias is more significant relative to the signal than an analogous bias found when delensing CMB B modes. We calculate the leading term of this bias, which is present even in the absence of lensing. We also demonstrate one method to remove this bias, using reconstructions from CMB angular scales within given ranges to delens CMB scales outside of those ranges. Some details relevant for a realistic analysis are also discussed, such as the importance of removing mask-induced effects for successful delensing, and a useful null test, obtained from randomizing the phases of the reconstructed potential. Our findings should help current and next-generation CMB experiments obtain tighter parameter constraints via the internal removal of lensing-induced smoothing from temperature and E-mode acoustic peaks.
AB - We present a method to delens the acoustic peaks of the cosmic microwave background (CMB) temperature and polarization power spectra internally, using lensing maps reconstructed from the CMB itself. We find that when delensing CMB acoustic peaks with a lensing potential map derived from the same CMB sky, a large bias arises in the delensed power spectrum. The cause of this bias is that the noise in the reconstructed potential map is derived from, and hence correlated with, the CMB map when delensing. This bias is more significant relative to the signal than an analogous bias found when delensing CMB B modes. We calculate the leading term of this bias, which is present even in the absence of lensing. We also demonstrate one method to remove this bias, using reconstructions from CMB angular scales within given ranges to delens CMB scales outside of those ranges. Some details relevant for a realistic analysis are also discussed, such as the importance of removing mask-induced effects for successful delensing, and a useful null test, obtained from randomizing the phases of the reconstructed potential. Our findings should help current and next-generation CMB experiments obtain tighter parameter constraints via the internal removal of lensing-induced smoothing from temperature and E-mode acoustic peaks.
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U2 - 10.1103/PhysRevD.95.103512
DO - 10.1103/PhysRevD.95.103512
M3 - Article
AN - SCOPUS:85020219808
SN - 2470-0010
VL - 95
JO - Physical Review D
JF - Physical Review D
IS - 10
M1 - 103512
ER -