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Data Products

Wilkinson Microwave Anisotropy Probe

Product Name
MCMC Foreground Maps
Mission
WMAP
Coord. System
Galactic
Projection Type
HEALPix, nested, res 6 (Nside=64)
Resolution
1°
Download Data
Base Model
Shifted Spinning Dust
Steepening Synchrotron

Description

These maps were generated from the MCMC fit described in Gold, et.al.. The inputs are the one degree smoothed maps per frequency band, binned to Nside=64. There is an MCMC chain for each pixel which is used to estimate the likelihood for all the parameters. The maps provided for each parameter are:

  • The best-fit parameter (i.e. peak likelihood) from each chain.
  • The mean parameter over the chain.
  • The marginalized variance.

Three sets of maps are provided: a "base" model, a shifted spinning dust model, and a steepening synchrotron model. Each model has a slightly different set of parameters that are allowed to vary.

The following parameters are allowed to vary when performing the fit at each pixel:

Parameter Notes
Synchrotron temperature at K-band All three models.
Free-free temperature at K-band All three models.
Dust temperature at W-band All three models.
Synchrotron spectral index Base and steepening synchrotron models only. Fixed to -3.0 in the shifted spinning dust model.
Dust spectral index Base model only; fixed to +2.0 in the other two models.
CMB temperature Thermodynamic units. All three models.
Synchrotron Stokes Q at K-band All three models.
Dust Stokes Q at W-band All three models.
CMB Stokes Q Thermodynamic units. All three models.
CMB Stokes U Thermodynamic units. All three models.
Spinning Dust Temperature at K-band Shifted spinning dust model only.
Synchrotron Steepening Parameter Steepening synchrotron model only.
Error flags. All three models. Each pixel is bit-coded:
  • 0 - no error
  • 1 - did not find a good adaptive stepsize in the "prechain" for that pixel, but the chain was run anyway
  • 2 - the chain for that pixel failed the convergence test
  • 4 - not used
  • 8 - not used
  • 16 - pixel was masked before processing, no fit was done
Best fit reduced χ2 All three models.

Parameters Derived from Stokes Q using K-band Polarization Directions
Synchrotron Stokes U at K-band All three models.
Dust Stokes U at W-band All three models.

Temperatures in mK are in antenna units except for the CMB maps, which are provided in thermodymanic units.

The reduced χ2 are the best-fit χ2 divided by the number of degrees of freedom determined from the chain using the "effective complexity".

Additional Information

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  • Page Updated: Wednesday, 19-Nov-2008
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