CMB Polarization and Temperature Power Spectra Estimation using Linear
  Combination of WMAP 5-year Maps
  We estimate CMB polarization and temperature power spectra using WMAP 5-year
foreground contaminated maps. The power spectrum is estimated by using a model
independent method, which does not utilize directly the diffuse foreground
templates nor the detector noise model. The method essentially consists of two
steps, (i) removal of diffuse foregrounds contamination by making linear
combination of individual maps in harmonic space and (ii) cross-correlation of
foreground cleaned maps to minimize detector noise bias. For temperature power
spectrum we also estimate and subtract residual unresolved point source
contamination in the cross-power spectrum using the point source model provided
by the WMAP science team. Our $TT$, $TE$ and $EE$ power spectra are in good
agreement with the published results of the WMAP science team. The error bars
on the polarization power spectra, however, turn out to be smaller in
comparison to what is obtained by the WMAP science team. We perform detailed
numerical simulations to test for bias in our procedure. We find that the bias
is small in all cases. A negative bias at low $l$ in $TT$ power spectrum has
been pointed in an earlier publication. We find that the bias corrected
quadrupole power ($l(l+1)C_l/2\pi)$ is 532 $\mu K^2$, approximately 2.5 times
the estimate (213.4 $\mu K^2$) made by the WMAP team.
