Improved Constraints on Cosmic Microwave Background Circular Polarization with CLASS
Abstract
We present improved constraints on circular polarization in the cosmic microwave background (CMB) from the Cosmology Large Angular Scale Surveyor (CLASS) experiment using data at 90, 150, and 220 GHz to complement previous results based on 40 GHz data alone. We extend constraints on circular polarization from the atmosphere to all CLASS frequencies and compare with a model of the atmospheric circular polarization spectrum. The inclusion of data at all CLASS frequencies improves upper limits on circular polarization, Stokes V, in the CMB by a factor of ∼ 5 at the largest angular scales (10 < ℓ < 30) and extends the constraints to smaller angular scales, ℓ = 700. In combination with Planck temperature data, we provide the first limits on the temperature-circular-polarization (TV) power spectrum to date. Both circular polarization (VV) and TV power spectra are consistent with zero, and CLASS places upper limits of 5.4 × 10−3 μKCMB2 on VV at large angular scale (10 < ℓ < 30) and 5.8 × 10−1 μKCMB2 on TV at 95% confidence at 30 < ℓ < 50.
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BibTeX
@misc{essingerhileman2026improved,
title = {{Improved Constraints on Cosmic Microwave Background Circular Polarization with CLASS}},
author = {Thomas Essinger-Hileman and Caleigh Ryan and Yunyang Li and Matthew A. Petroff and John W. Appel and Charles L. Bennett and Ricardo Bustos and Carol Yan Yan Chan and David T. Chuss and Joseph Cleary and Sumit Dahal and Rahul Datta and Jullianna Denes Couto and Kevin L. Denis and Joseph R. Eimer and Joseph E. Golec and Kyle R. Helson and Jeffrey Iuliano and Tobias A. Marriage and Jeffrey J. McMahon and Ivan Padilla and Carolina Morales Perez and Karwan Rostem and Rui Shi and Deniz A. N. Valle and Duncan J. Watts and Janet L. Weiland and Edward J. Wollack},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.40125},
eprint = {2609.40125},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.40125},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Improved Constraints on Cosmic Microwave Background Circular Polarization with CLASS
AU - Thomas Essinger-Hileman
AU - Caleigh Ryan
AU - Yunyang Li
AU - Matthew A. Petroff
AU - John W. Appel
AU - Charles L. Bennett
AU - Ricardo Bustos
AU - Carol Yan Yan Chan
AU - David T. Chuss
AU - Joseph Cleary
AU - Sumit Dahal
AU - Rahul Datta
AU - Jullianna Denes Couto
AU - Kevin L. Denis
AU - Joseph R. Eimer
AU - Joseph E. Golec
AU - Kyle R. Helson
AU - Jeffrey Iuliano
AU - Tobias A. Marriage
AU - Jeffrey J. McMahon
AU - Ivan Padilla
AU - Carolina Morales Perez
AU - Karwan Rostem
AU - Rui Shi
AU - Deniz A. N. Valle
AU - Duncan J. Watts
AU - Janet L. Weiland
AU - Edward J. Wollack
PY - 2026
DA - 2026/09/30
PB - arXiv
DO - 10.48550/arxiv.2609.40125
UR - https://arxiv.org/abs/2609.40125
AB - We present improved constraints on circular polarization in the cosmic microwave background (CMB) from the Cosmology Large Angular Scale Surveyor (CLASS) experiment using data at 90, 150, and 220 GHz to complement previous results based on 40 GHz data alone. We extend constraints on circular polarization from the atmosphere to all CLASS frequencies and compare with a model of the atmospheric circular polarization spectrum. The inclusion of data at all CLASS frequencies improves upper limits on circular polarization, Stokes V, in the CMB by a factor of ∼ 5 at the largest angular scales (10 < ℓ < 30) and extends the constraints to smaller angular scales, ℓ = 700. In combination with Planck temperature data, we provide the first limits on the temperature-circular-polarization (TV) power spectrum to date. Both circular polarization (VV) and TV power spectra are consistent with zero, and CLASS places upper limits of 5.4 × 10^−3 μK_CMB^2 on VV at large angular scale (10 < ℓ < 30) and 5.8 × 10^−1 μK_CMB^2 on TV at 95% confidence at 30 < ℓ < 50.
ER -