Logo
ScienceStack
Table of Contents
Fetching ...
Sign In

Detection of B-mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope

D. Hanson, S. Hoover, A. Crites, P. A. R. Ade, K. A. Aird, J. E. Austermann, J. A. Beall, A. N. Bender, B. A. Benson, L. E. Bleem, J. J. Bock, J. E. Carlstrom, C. L. Chang, H. C. Chiang, H-M. Cho, A. Conley, T. M. Crawford, T. de Haan, M. A. Dobbs, W. Everett, J. Gallicchio, J. Gao, E. M. George, N. W. Halverson, N. Harrington, J. W. Henning, G. C. Hilton, G. P. Holder, W. L. Holzapfel, J. D. Hrubes, N. Huang, J. Hubmayr, K. D. Irwin, R. Keisler, L. Knox, A. T. Lee, E. Leitch, D. Li, C. Liang, D. Luong-Van, G. Marsden, J. J. McMahon, J. Mehl, S. S. Meyer, L. Mocanu, T. E. Montroy, T. Natoli, J. P. Nibarger, V. Novosad, S. Padin, C. Pryke, C. L. Reichardt, J. E. Ruhl, B. R. Saliwanchik, J. T. Sayre, K. K. Schaffer, B. Schulz, G. Smecher, A. A. Stark, K. Story, C. Tucker, K. Vanderlinde, J. D. Vieira, M. P. Viero, G. Wang, V. Yefremenko, O. Zahn, M. Zemcov

Abstract

Gravitational lensing of the cosmic microwave background generates a curl pattern in the observed polarization. This "B-mode" signal provides a measure of the projected mass distribution over the entire observable Universe and also acts as a contaminant for the measurement of primordial gravity-wave signals. In this Letter we present the first detection of gravitational lensing B modes, using first-season data from the polarization-sensitive receiver on the South Pole Telescope (SPTpol). We construct a template for the lensing B-mode signal by combining E-mode polarization measured by SPTpol with estimates of the lensing potential from a Herschel-SPIRE map of the cosmic infrared background. We compare this template to the B modes measured directly by SPTpol, finding a non-zero correlation at 7.7 sigma significance. The correlation has an amplitude and scale-dependence consistent with theoretical expectations, is robust with respect to analysis choices, and constitutes the first measurement of a powerful cosmological observable.

Detection of B-mode Polarization in the Cosmic Microwave Background with Data from the South Pole Telescope

Abstract

Gravitational lensing of the cosmic microwave background generates a curl pattern in the observed polarization. This "B-mode" signal provides a measure of the projected mass distribution over the entire observable Universe and also acts as a contaminant for the measurement of primordial gravity-wave signals. In this Letter we present the first detection of gravitational lensing B modes, using first-season data from the polarization-sensitive receiver on the South Pole Telescope (SPTpol). We construct a template for the lensing B-mode signal by combining E-mode polarization measured by SPTpol with estimates of the lensing potential from a Herschel-SPIRE map of the cosmic infrared background. We compare this template to the B modes measured directly by SPTpol, finding a non-zero correlation at 7.7 sigma significance. The correlation has an amplitude and scale-dependence consistent with theoretical expectations, is robust with respect to analysis choices, and constitutes the first measurement of a powerful cosmological observable.

Paper Structure

This paper contains 1 equation, 3 figures.

Figures (3)

  • Figure 1: Left: Wiener-filtered $E$-mode polarization measured by SPTpol at $150$ GHz. Center: Wiener-filtered CMB lensing potential inferred from CIB fluctuations measured by Herschel at $500\,\mu \mathrm{m}$. Right: gravitational lensing $B$-mode estimate synthesized using Eq. \ref{['eqn:blen']}. The lower left corner of each panel indicates the blue(-)/red(+) color scale.
  • Figure 2: Black, center bars: cross correlation of the lensing $B$ modes measured by SPTpol at $150$ GHz with lensing $B$ modes inferred from CIB fluctuations measured by Herschel and $E$ modes measured by SPTpol at $150\,$GHz; as shown in Fig. \ref{['fig:map_ebp_tri']}. Green, left-offset bars: same as black, but using $E$ modes measured at $95$ GHz, testing both foreground contamination and instrumental systematics. Orange, right-offset bars: same as black, but with $B$ modes obtained using the $\chi_B$ procedure described in the text rather than our fiducial Wiener filter. Gray bars: curl-mode null test as described in the text. Dashed black curve: lensing $B$-mode power spectrum in the fiducial cosmological model.
  • Figure 3: "Lensing view" of the $EB\phi$ correlation plotted in Fig. \ref{['fig:plot_cl_ep_b_pub']}, in which we cross-correlate an $EB$ lens reconstruction from SPTpol data with CIB intensity fluctuations measured by Herschel. Left green, center black, and right orange bars are as described in Fig. \ref{['fig:plot_cl_ep_b_pub']}. Previous analyses using temperature-based lens reconstruction from PlanckAde:2013aro and SPT-SZ Holder:2013hqu are shown with boxes. The results of Ref. Ade:2013aro are at a nominal wavelength of $550\,\mu \mathrm{m}$, which we scale to $500\,\mu \mathrm{m}$ with a factor of $1.22$Gispert:2000np. The dashed black curve gives our fiducial model for $C_l^{{\rm CIB}\hbox{-}\phi}$ as described in the text.