A Measurement of the Largest-scale CMB <i>E</i>-mode Polarization with CLASS

Abstract We present measurements of large-scale cosmic microwave background E -mode polarization from the Cosmology Large Angular Scale Surveyor 90 GHz data. Using 115 det-yr of observations collected through 2024 with a variable-delay polarization modulator, we achieved a polarization sensitivity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>82</mml:mn> <mml:mspace width="0.25em"/> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">K</mml:mi> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">arcmin</mml:mi> </mml:math> , comparable to Planck at similar frequencies (100 and 143 GHz ). The analysis demonstrates effective mitigation of systematic errors and addresses challenges to large-angular-scale power recovery posed by time-domain filtering in maximum-likelihood map-making. A novel implementation of the pixel-space transfer matrix is introduced, which enables efficient filtering simulations and bias correction in the power spectrum using the quadratic cross-spectrum estimator. Overall, we achieved an unbiased time-domain filtering correction to recover the largest angular scale polarization, with the only power deficit, arising from map-making nonlinearity, being characterized as &lt;3%. Through cross-correlation with Planck, we detected the cosmic reionization at 99.4% significance and measured the reionization optical depth <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>τ</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.05</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.019</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.018</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , marking the first ground-based attempt at such a measurement. At intermediate angular scales ( ℓ &gt; 30), our results, both independently and in cross-correlation with Planck, remain fully consistent with Planck’s measurements.

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Publication Details

Journal
The Astrophysical Journal
Published
2025-06-11
DOI
https://doi.org/10.3847/1538-4357/adc723
Citations
9
Primary Topic
Cosmology and Gravitation Theories
Type
article
Field-Weighted Citation Impact
10.39
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article

A Measurement of the Largest-scale CMB E-mode Polarization with CLASS

Joseph Cleary, Yan Yan Chan, Matthew A. Petroff, Carolina Morales Pérez et al.
9 citations
The Astrophysical Journal
Cosmology and Gravitation Theories
10.39
article

A Measurement of the Largest-scale CMB E-mode Polarization with CLASS

Joseph Cleary, Yan Yan Chan, Matthew A. Petroff, Carolina Morales Pérez, David T. Chuss, Kathleen Harrington, Sarah Marie Bruno, Duncan J. Watts, Deniz A. N. Valle, R. Reeves, Lucas Parker, Tobias A. Marriage, Joseph R. Eimer, Jullianna Denes Couto, Rolando Dünner, Kevin L. Denis, John W. Appel, Zhilei Xu, Thomas Essinger-Hileman, Lingzhen Zeng, Sumit Dahal, Karwan Rostem, Rahul Datta, C. L. Bennett, Jeffrey Iuliano, Ricardo Bustos, Yunyang Li, Kyle Helson, N. J. Miller, J. L. Weiland, John Karakla, Edward J. Wollack, Johannes Hubmayr, Rui Shi, Koji Shukawa, Caleigh Ryan, Michael K. Brewer
article en
9 citations

Abstract

Abstract We present measurements of large-scale cosmic microwave background E -mode polarization from the Cosmology Large Angular Scale Surveyor 90 GHz data. Using 115 det-yr of observations collected through 2024 with a variable-delay polarization modulator, we achieved a polarization sensitivity of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>82</mml:mn> <mml:mspace width="0.25em"/> <mml:mi>μ</mml:mi> <mml:mi mathvariant="normal">K</mml:mi> <mml:mspace width="0.25em"/> <mml:mi mathvariant="normal">arcmin</mml:mi> </mml:math> , comparable to Planck at similar frequencies (100 and 143 GHz ). The analysis demonstrates effective mitigation of systematic errors and addresses challenges to large-angular-scale power recovery posed by time-domain filtering in maximum-likelihood map-making. A novel implementation of the pixel-space transfer matrix is introduced, which enables efficient filtering simulations and bias correction in the power spectrum using the quadratic cross-spectrum estimator. Overall, we achieved an unbiased time-domain filtering correction to recover the largest angular scale polarization, with the only power deficit, arising from map-making nonlinearity, being characterized as &lt;3%. Through cross-correlation with Planck, we detected the cosmic reionization at 99.4% significance and measured the reionization optical depth <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mi>τ</mml:mi> <mml:mo>=</mml:mo> <mml:mn>0.05</mml:mn> <mml:msubsup> <mml:mrow> <mml:mn>3</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.019</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>0.018</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> , marking the first ground-based attempt at such a measurement. At intermediate angular scales ( ℓ &gt; 30), our results, both independently and in cross-correlation with Planck, remain fully consistent with Planck’s measurements.

The Astrophysical JournalVol. 986(2)
Openalex Percentile: Top 2%
Cosmology and Gravitation Theories
10.39
DOIOpen Access PDFOpenAlex
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