Wilkinson Microwave Anisotropy Probe

These maps were generated from the "base" 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.

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

• Synchrotron temperature at K-band
• Free-free temperature at K-band
• Dust temperature at W-band
• Synchrotron spectral index
• Dust spectral index
• CMB temperature (thermodynamic units)
• Synchrotron Stokes Q at K-band
• Dust Stokes Q at W-band
• CMB Stokes Q (thermodynamic units)
• CMB Stokes U (thermodynamic units)
• Error flags. 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 map.

Two additional parameters are derived from the Stokes Q parameters using K-band polarization directions:

• Synchrotron Stokes U at K-band
• Dust Stokes U at W-band

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

• Five-Year Wilkinson Microwave Anisotropy Probe (WMAP) Observations: Galactic Foreground Emission, B. Gold, et.al. (2008)
• WMAP Five Year Explanatory Supplement

Back to Product Page