Foreground Analysis Using Cross-Correlations of External Templates on
  the 7-year WMAP data
  WMAP data when combined with ancillary data on free-free, synchrotron and
dust allow an improved understanding of the spectrum of emission from each of
these components. Here we examine the sky variation at intermediate and high
latitudes using a cross-correlation technique. In particular, we compare the
observed emission in several large partitions of the sky plus 33 selected sky
regions to three "standard" templates. The regions are selected using a
criterion based on the morphology of these template maps. The synchrotron
emission shows evidence of steepening between GHz frequencies and the
\emph{WMAP} bands. There are indications of spectral index variations across
the sky but the current data are not precise enough to accurately quantify this
from region-to-region. The emission correlated with the $H_{\alpha}$ template
shows clear evidence of deviation from a free-free spectrum. The emission can
be decomposed into a contribution from both free-free and spinning dust in the
warm ionised medium of the Galaxy. The derived free-free emissivity corresponds
to a mean electron temperature of $\sim 6000$ K, although the value depends
critically on the impact of dust absorption on the $H_{\alpha}$ intensity. The
WIM spinning dust emission has a peak emission in intensity in the range 40--50
GHz. The anomalous microwave emission associated with dust is detected at high
significance in most of the 33 fields studied. The anomalous emission
correlates well with the Finkbeiner et al. (1999) model 8 predictions (FDS8) at
94 GHz, and is well described globally by a power-law emission model with an
effective spectral index between 20 and 60 GHz of $\beta \approx -2.7$. It is
clear that attempts to explain the emission by spinning dust models require
multiple components, which presumably relates to a complex mix of emission
regions along a given line-of-sight.
