PreprintarXiv licencearXiv
De-lensing cosmic birefringence with joint reconstruction
Abstract
Reconstruction of anisotropic cosmic birefringence from the CMB is limited by lensing B-mode sample variance and partially degenerate with the lensing curl. We study the joint reconstruction of lensing (gradient and curl) and birefringence at the maximum-a-posteriori point, whose spectra are near-optimal statistics. We predict the joint response and noise analytically, validate them on simulations, and show unbiased inference of its amplitude. Errors will shrink $5$-fold relative to quadratic estimators at SPT-3G+ depths, promising much tighter constraints on parity-violating new physics, owing to the removal of the lensing B-polarization sample variance.
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BibTeX
@misc{belkner2026delensing,
title = {{De-lensing cosmic birefringence with joint reconstruction}},
author = {Sebastian Belkner and Julien Carron},
howpublished = {arXiv},
year = {2026},
month = nov,
doi = {10.48550/arxiv.2611.03761},
eprint = {2611.03761},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2611.03761},
}
RIS
TY - UNPB
TI - De-lensing cosmic birefringence with joint reconstruction
AU - Sebastian Belkner
AU - Julien Carron
PY - 2026
DA - 2026/11/02
PB - arXiv
DO - 10.48550/arxiv.2611.03761
UR - https://arxiv.org/abs/2611.03761
AB - Reconstruction of anisotropic cosmic birefringence from the CMB is limited by lensing B-mode sample variance and partially degenerate with the lensing curl. We study the joint reconstruction of lensing (gradient and curl) and birefringence at the maximum-a-posteriori point, whose spectra are near-optimal statistics. We predict the joint response and noise analytically, validate them on simulations, and show unbiased inference of its amplitude. Errors will shrink $5$-fold relative to quadratic estimators at SPT-3G+ depths, promising much tighter constraints on parity-violating new physics, owing to the removal of the lensing B-polarization sample variance.
ER -