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Physique Théorique


New Planck results, another one bites the dust

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optimized-polar planck

After four years of operation of the Planck satellite of the European Space Agency (ESA), the Planck Collaboration has build up an exquisitely precise map of the sky in both temperature and now of polarisation. These maps furnish a detailed picture of how the universe evolved. Among the numerous results provided by the Planck satellite over the last year, there is an assessment of the polarised dust emission at intermediate and high Galactic latitudes  (http://arxiv.org/abs/1409.5738). This is a crucial foreground in the searches for primordial B-mode polarisation patterns, possibly imprinted in the Cosmic Microwave Background by gravitational waves of  inflationary origin, also known as tensor modes. Thanks to this measurement, older estimates of this contribution have  been revisited and, in a joint effort by the BICEP2/Keck Array and Planck Data collaborations (http://arxiv.org/abs/1502.00612),  no statistically significant evidence for tensor modes has been found in a reanalysis of the BICEP 2 observations, which  in 2014 had been interpreted as a possible primordial B-mode detection  (http://arxiv.org/abs/1403.3985), an interpretation that made big waves in the media then... undeservedly. We will need to wait and be more careful about gravity waves.