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SUMMARY:Towards efficient CMB analysis on an incomplete sky - Helge Grütj
 en (Damtp) 
DTSTART:20130603T120000Z
DTEND:20130603T130000Z
UID:TALK44372@talks.cam.ac.uk
CONTACT:Camille Bonvin
DESCRIPTION:In principle the statistics of the CMB are simple. The fluctua
 tions are to a very good approximation an isotropic Gaussian random field 
 and the distribution of their multipole coefficients is entirely character
 ised by the power spectrum. This means that\, with access to the true mult
 ipoles\, using the full information content of the CMB to study cosmology 
 becomes a straightforward task.\nUnfortunately it is impossible to measure
  the actual multipole coefficients of the fluctuations. Foreground contami
 nation of the data requires masking of the sky and introduces complicated 
 correlations between the measured multipoles. This turns CMB analysis into
  a complicated and computationally demanding problem. Likelihood functions
  cannot be evaluated exactly any longer but feasible estimation methods li
 ke the popular pseudo-Cell estimation tend to lose information on cosmolog
 y.\n\nI will talk about recent work that aims at avoiding information loss
  in the analysis of the CMB anisotropies on a masked sky. In particular I 
 will present an approach that extends the standard pseudo-Cell method and 
 gives rise to numerically tractable estimators that recover the lost infor
 mation and produce estimates that are close to optimal.
LOCATION:CMS\, Pav.B\, CTC Common Room (B1.19)
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