Measurements of B-mode Polarization of the Cosmic Microwave Background from 500 Square Degrees of SPTpol Data

Abstract

We report a B-mode power spectrum measurement from the cosmic microwave background (CMB) polarization anisotropy observations made using the SPTpol instrument on the South Pole Telescope. This work uses 500 deg${}^2$ of SPTpol data, a five-fold increase over the last SPTpol B-mode release. As a result, the bandpower uncertainties have been reduced by more than a factor of two, and the measurement extends to lower multipoles: $52<\ell <2301$. Data from both 95 and 150 GHz are used, allowing for three cross-spectra: 95 GHz x 95 GHz, 95 GHz x 150 GHz, and 150 GHz x 150 GHz. B-mode power is detected at very high significance; we find $P(BB<0)=5.8\times 10^{-71}$, corresponding to a $18.1\ddot{I}ƒ$ detection of power. An upper limit is set on the tensor-to-scalar ratio, $r<0.44$ at 95% confidence (the expected $1\ddot{I}ƒ$ constraint on $r$ given the measurement uncertainties is 0.22). We find the measured B-mode power is consistent with the Planck best-fit $\hat{I}›$CDM model predictions. Scaling the predicted lensing B-mode power in this model by a factor Alens, the data prefer Alens = $1.17\pm 0.13$. These data are currently the most precise measurements of B-mode power at $\ell >320$.

16 pages, 4 figures, Submitted to PRD