Wilkinson Microwave Anisotropy Probe DR4
The data made available through this page has been updated. The most recent version of this data may be accessed through https://lambda.gsfc.nasa.gov/product/wmap/current/"
DR4 Foreground Templates
HEALPix, nested, res 9 (Nside=512) or res 4 (Nside=16)
For most cosmological analyses one must retain the well-defined noise characteristics of the WMAP frequency band maps. To achieve this, low-noise model templates for each foreground emission component (dust, free-free, and synchrotron) were created and fit to the maps at each frequency band; these fits were then subtracted from the skymaps. Regions that could not be reliably cleaned were masked, and thereby essentially discarded from later analysis.
Dust emission "Model 8" from Finkbeiner et.al. (FDS 1999) was evaluated at 94 GHz and used as the basis for the dust intensity templates. This 94GHz dust map, smoothed to 1 degree, was used as the dust emission template for Stokes I/temperature analysis. A separate dust template was developed for Q and U polarization analysis, combining information from the FDS intensity map and starlight polarization maps. This latter template is stored in a standard HEALpix FITS map file with the Q and U templates stored in the Q_POLARISATION and U_POLARISATION columns of the first binary table extension; the TEMPERATURE and N_OBS columns of this extention are set to zero and one, respectively.
The free-free emission template was developed from the full-sky Hα map compiled by Finkbeiner (2003) with a correction for dust extinction (Bennett, et.al., 2003).
The synchrotron template used for temperature analysis was computed from the difference of the WMAP K and Ka Stokes I maps in thermodynamic units, using the five year maps smoothed to 1° resolution. The procedure for creating the template is described in detail in Hinshaw, et.al. (2007). K band data was used for the polarized synchrotron emission template as described by Page, et.al. (2007)
The free-free emission template and the temperature and polarization dust emission templates are available through the Download Data link given above. The remaining templates are available through other avenues on LAMBDA and are described above.