Wilkinson Microwave Anisotropy Probe

The data made available through this page has been updated. The most recent version of this data may be accessed through /product/map/current/

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

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

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