A Measurement of the Cosmic Microwave Background Gravitational Lensing Potential from 100 Square Degrees of SPTpol Data

• Published in: The Astrophysical Journal
• Main Authors: Story, K. T., Crites, A. T., Padin, S.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Astronomical Society 2015
• Subjects: South Pole; South pole
• Online Access: https://authors.library.caltech.edu/61630/; https://authors.library.caltech.edu/61630/1/Story_2015.pdf; https://authors.library.caltech.edu/61630/2/1412.4760v2.pdf; https://resolver.caltech.edu/CaltechAUTHORS:20151028-100055139

We present a measurement of the cosmic microwave background (CMB) gravitational lensing potential using data from the first two seasons of observations with SPTpol, the polarization-sensitive receiver currently installed on the South Pole Telescope. The observations used in this work cover 100 deg^2 of sky with arcminute resolution at 150 GHz. Using a quadratic estimator, we make maps of the CMB lensing potential from combinations of CMB temperature and polarization maps. We combine these lensing potential maps to form a minimum-variance (MV) map. The lensing potential is measured with a signal-to-noise ratio of greater than one for angular multipoles between 100 < L < 250. This is the highest signal-to-noise mass map made from the CMB to date and will be powerful in cross-correlation with other tracers of large-scale structure. We calculate the power spectrum of the lensing potential for each estimator, and we report the value of the MV power spectrum between 100 < L < 2000 as our primary result. We constrain the ratio of the spectrum to a fiducial ΛCDM model to be A_(MV) = 0.92 ± 0.14 (Stat.) ± 0.08 (Sys.). Restricting ourselves to polarized data only, we find A_(POL) = 0.92 ± 0.24 (Stat.) ± 0.11 (Sys.). This measurement rejects the hypothesis of no lensing at 5.9σ using polarization data alone, and at 14σ using both temperature and polarization data.