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South Pole Telescope


July 22, 2013: Detection of B-mode Polarization by SPTpol.

 

 

December 23, 2011: The two-dimensional marginalized constraints on the sum of the neutrino masses versus the number of relativistic species. Contours show the 68% and 95% confidence regions for the WMAP7+H0+BAO (gray, dashed) dataset, then including the SPT power spectrum measurements from Keisler et al. (2011) (blue, dashed), and next including the SPT cluster abundance measurements from Benson et al. (2011) (orange, solid). The dashed vertical line shows the expected value for three neutrino species.



 

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July, 2013: B-mode polarization detected with SPTpol.

Scientists from the South Pole Telescope (SPT) project have detected subtle distortions referred to as 'B-modes' in the polarization of the Cosmic Microwave Background (CMB, preprint here). These distortions---detected for the first time in data from SPTpol, the polarization-sensitive receiver installed on the SPT in January, 2012---are thought to have only two sources: gravitational lensing of the more conventional 'E-mode' CMB polarization, and a background of gravitational waves from the epoch of cosmic inflation. The signals detected by SPTpol are due to gravitational lensing, and a sufficiently sensitive measurement of these signals will help us learn about neutrinos through their impact on the growth of structure in the universe. Successfully detecting this tiny B-mode signal also represents a major milestone along the way to using the CMB to learn about the earliest moments of the universe with the inflationary B modes.

 
 
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