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A measurement of the CMB E-mode angular power spectrum at subdegree scales from 670 square degrees of POLARBEAR data

S. Adachi, M. A. O. Aguilar Faúndez, K. Arnold, C. Baccigalupi, D. Barron, D. Beck, F. Bianchini, S. Chapman, K. Cheung, Y. Chinone, K. Crowley, M. Dobbs, H. El Bouhargani, T. Elleflot, J. Errard, G. Fabbian, C. Feng, T. Fujino, N. Galitzki, N. Goeckner-Wald, J. Groh, G. Hall, M. Hasegawa, M. Hazumi, H. Hirose, A. H. Jaffe, O. Jeong, D. Kaneko, N. Katayama, B. Keating, S. Kikuchi, T. Kisner, A. Kusaka, A. T. Lee, D. Leon, E. Linder, L. N. Lowry, F. Matsuda, T. Matsumura, Y. Minami, M. Navaroli, H. Nishino, A. T. P. Pham, D. Poletti, C. L. Reichardt, Y. Segawa, P. Siritanasak, O. Tajima, S. Takakura, S. Takatori, D. Tanabe, G. P. Teply, C. Tsai, C. Vergès, B. Westbrook, Y. Zhou

TL;DR

POLARBEAR delivers a high-significance measurement of the CMB $E$-mode power spectrum over $500 \leq \ell < 3000$ using a 670 deg$^2$ 150 GHz survey, enabling detailed tests of $\Lambda$CDM and constraints on extensions when combined with Planck and other datasets. The analysis relies on end-to-end simulations, pseudo-$C_\ell$ cross-spectra, careful beam and transfer-function characterization, and a rigorously estimated covariance to extract the $EE$ spectrum across the third to seventh acoustic peaks. The results are consistent with $\Lambda$CDM, improve constraints on $H_0$, $N_{\rm eff}$, and $Y_{\rm He}$, and show no strong evidence for new physics; nevertheless, the $H_0$ tension persists. Looking forward, the gathered measurements validate ground-based $E$-mode polarization as a powerful cosmological probe and foreshadow substantial gains with the upcoming Simons Array.

Abstract

We report a measurement of the E-mode polarization power spectrum of the cosmic microwave background (CMB) using 150 GHz data taken from July 2014 to December 2016 with the POLARBEAR experiment. We reach an effective polarization map noise level of $32\,μ\mathrm{K}$-$\mathrm{arcmin}$ across an observation area of 670 square degrees. We measure the EE power spectrum over the angular multipole range $500 \leq \ell <3000$, tracing the third to seventh acoustic peaks with high sensitivity. The statistical uncertainty on E-mode bandpowers is $\sim 2.3 μ{\rm K}^2$ at $\ell \sim 1000$ with a systematic uncertainty of 0.5$μ{\rm K}^2$. The data are consistent with the standard $Λ$CDM cosmological model with a probability-to-exceed of 0.38. We combine recent CMB E-mode measurements and make inferences about cosmological parameters in $Λ$CDM as well as in extensions to $Λ$CDM. Adding the ground-based CMB polarization measurements to the Planck dataset reduces the uncertainty on the Hubble constant by a factor of 1.2 to $H_0 = 67.20 \pm 0.57 {\rm km\,s^{-1} \,Mpc^{-1}}$. When allowing the number of relativistic species ($N_{eff}$) to vary, we find $N_{eff} = 2.94 \pm 0.16$, which is in good agreement with the standard value of 3.046. Instead allowing the primordial helium abundance ($Y_{He}$) to vary, the data favor $Y_{He} = 0.248 \pm 0.012$. This is very close to the expectation of 0.2467 from Big Bang Nucleosynthesis. When varying both $Y_{He}$ and $N_{eff}$, we find $N_{eff} = 2.70 \pm 0.26$ and $Y_{He} = 0.262 \pm 0.015$.

A measurement of the CMB E-mode angular power spectrum at subdegree scales from 670 square degrees of POLARBEAR data

TL;DR

POLARBEAR delivers a high-significance measurement of the CMB -mode power spectrum over using a 670 deg 150 GHz survey, enabling detailed tests of CDM and constraints on extensions when combined with Planck and other datasets. The analysis relies on end-to-end simulations, pseudo- cross-spectra, careful beam and transfer-function characterization, and a rigorously estimated covariance to extract the spectrum across the third to seventh acoustic peaks. The results are consistent with CDM, improve constraints on , , and , and show no strong evidence for new physics; nevertheless, the tension persists. Looking forward, the gathered measurements validate ground-based -mode polarization as a powerful cosmological probe and foreshadow substantial gains with the upcoming Simons Array.

Abstract

We report a measurement of the E-mode polarization power spectrum of the cosmic microwave background (CMB) using 150 GHz data taken from July 2014 to December 2016 with the POLARBEAR experiment. We reach an effective polarization map noise level of - across an observation area of 670 square degrees. We measure the EE power spectrum over the angular multipole range , tracing the third to seventh acoustic peaks with high sensitivity. The statistical uncertainty on E-mode bandpowers is at with a systematic uncertainty of 0.5. The data are consistent with the standard CDM cosmological model with a probability-to-exceed of 0.38. We combine recent CMB E-mode measurements and make inferences about cosmological parameters in CDM as well as in extensions to CDM. Adding the ground-based CMB polarization measurements to the Planck dataset reduces the uncertainty on the Hubble constant by a factor of 1.2 to . When allowing the number of relativistic species () to vary, we find , which is in good agreement with the standard value of 3.046. Instead allowing the primordial helium abundance () to vary, the data favor . This is very close to the expectation of 0.2467 from Big Bang Nucleosynthesis. When varying both and , we find and .

Paper Structure

This paper contains 22 sections, 15 equations, 5 figures, 3 tables.

Table of Contents

  1. Introduction
  2. The Polarbear 670 deg$^2$ survey
  3. Time-ordered data to maps
  4. Data selection and filtering of the time-ordered data
  5. Mapmaking
  6. Noise
  7. Beams and calibration
  8. Power spectrum analysis
  9. Apodization mask and mode-coupling matrix
  10. Simulations
  11. Filter transfer function and bandpower window functions
  12. Bandpower Covariance
  13. Data validation
  14. Bandpowers
  15. Cosmological implications
  16. ...and 7 more sections

Figures (5)

  • Figure 1: Measured Polarbear$E$-mode spectrum with included error bars from statistical uncertainties. The solid gray line represents the best-fit $\Lambda$CDM model from planck2015XIII. The bandpowers and statistical errors are listed in Table \ref{['spectrumtable']}.
  • Figure 2: Recent CMB $E$-mode power spectrum measurements from Planckplanck18-5, Polarbear, SPTpolhenning18, ACTpollouis17, and BICEP2/Keck bicepkeck18 have mapped out the $E$-mode power spectrum at high S/N from very large scales out to the ninth acoustic peak. The power spectrum measurements from the different experiments are in good agreement with each other. The data used in the parameter section of this work are shown by filled points. The solid gray line represents the best-fit $\Lambda$CDM model from planck2015XIII.
  • Figure 3: Posterior probability distribution function for the primordial helium abundance, $Y_{\rm He}$, for the three datasets. Adding the ground-based CMB data to Planck slightly shifts the preferred helium abundance towards the BBN prediction of $Y_{\rm He} \sim 0.2467$, but leads to only a minor reduction in the uncertainty. All three datasets are in good agreement with the BBN prediction.
  • Figure 4: Posteriors for the parameter subset $N_{\rm eff}$, $n_s$, and $\Omega_c h^2$ for the Planck, CMBselect, and CMBext datasets. Adding data beyond the Planck CMB bandpowers only modestly reduces the allowed parameter volume without significantly shifting the preferred values or breaking the parameter degeneracies.
  • Figure 5: Parameter posteriors for the $\Lambda$CDM+$Y_{\rm He}$+$N_{\rm eff}$ model. We have excluded the optical depth $\tau$ and amplitude of scalar perturbations $A_s$ to reduce the complexity of the figure as these two parameters change negligibly between the datasets.