Large-scale polarized foreground component separation for Planck

Charmaine Armitage-Caplan, Joanna Dunkley, Hans Kristian Eriksen, Clive Dickinson

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


We use Bayesian component estimation methods to examine the prospects of large-scale polarized map and cosmological parameter estimation with simulated Planck data assuming simplified white noise properties. The sky signal is parametrized as the sum of the cosmic microwave background (CMB), synchrotron emission, and thermal dust emission. The synchrotron and dust emission components are modelled as power laws in frequency, with a spatially varying spectral index for synchrotron and a uniform index for dust. Using the Gibbs sampling technique, we estimate the linear polarization Q and U posterior amplitudes of the CMB, synchrotron and dust maps as well as the two spectral indices in ~4°pixels. We use the recovered CMB map and its covariance in an exact pixel likelihood algorithm to estimate the optical depth to reionization τ, the tensor-to-scalar ratio r, and to construct conditional likelihood slices for CEE and CBB. Given our foreground model, we find σ(τ) ≈ 0.004 for τ= 0.1, σ(r) ≈ 0.03 for a model with r= 0.1, and a 95 per cent upper limit of r < 0.02 for r= 0.0.

Original languageEnglish (US)
Pages (from-to)1498-1510
Number of pages13
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
StatePublished - Dec 2011
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Cosmic background radiation
  • Cosmological parameters
  • Cosmology: observations


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