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CATEGORIES:Cosmology Lunch
SUMMARY:Towards efficient CMB analysis on an incomplete sk
y - Helge Grütjen (Damtp)
DTSTART;TZID=Europe/London:20130603T130000
DTEND;TZID=Europe/London:20130603T140000
UID:TALK44372AThttp://talks.cam.ac.uk
URL:http://talks.cam.ac.uk/talk/index/44372
DESCRIPTION:In principle the statistics of the CMB are simple.
The fluctuations are to a very good approximation
an isotropic Gaussian random field and the distri
bution of their multipole coefficients is entirely
characterised by the power spectrum. This means t
hat\, with access to the true multipoles\, using t
he full information content of the CMB to study co
smology becomes a straightforward task.\nUnfortuna
tely it is impossible to measure the actual multip
ole coefficients of the fluctuations. Foreground c
ontamination of the data requires masking of the s
ky and introduces complicated correlations between
the measured multipoles. This turns CMB analysis
into a complicated and computationally demanding p
roblem. Likelihood functions cannot be evaluated e
xactly any longer but feasible estimation methods
like the popular pseudo-Cell estimation tend to lo
se information on cosmology.\n\nI will talk about
recent work that aims at avoiding information loss
in the analysis of the CMB anisotropies on a mask
ed sky. In particular I will present an approach t
hat extends the standard pseudo-Cell method and gi
ves rise to numerically tractable estimators that
recover the lost information and produce estimates
that are close to optimal.
LOCATION:CMS\, Pav.B\, CTC Common Room (B1.19)
CONTACT:Camille Bonvin
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