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SUMMARY:Inference of the optical depth to reionization from low multipole 
 temperature and polarisation Planck data - Roger de Belsunce
DTSTART:20201118T140000Z
DTEND:20201118T143000Z
UID:TALK154162@talks.cam.ac.uk
CONTACT:Emma Curtis Lake
DESCRIPTION:I will talk about challenges arising in cosmological data anal
 ysis. Either likelihoods are intractable or systematics in the data cannot
  be properly modelled. How can we make reliable inference from noise-domin
 ated signals\, such as the optical depth to reionization (tau) in the CMB?
  Therefore\, I will present a simulation-based likelihood\, a likelihood a
 pproximation scheme and a density-estimation likelihood-free approach to c
 onstrain tau using data from the Planck space mission.\nI will present the
  first combined measurement of tau using temperature and polarisation data
  at low multipoles (2<ell<29) as it is most sensitive to tau in this regim
 e. Introducing more realistic noise modelling at different scales\, a rigo
 rous handling of systematics and the use of a quadratic cross-spectrum est
 imator\, we obtain a reliable error budget and an unbiased estimate of tau
 . We measure tau on foreground cleaned 100x143 GHz full-mission Planck 201
 8 and Sroll 2.0 maps.
LOCATION: Webinar  (via Zoom online)
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