In this paper, we propose & implement on WMAP 5-year data, a model
independent approach of foreground power spectrum estimation for multifrequency
observations of CMB experiments. Recently a model independent approach of CMB
power spectrum estimation was proposed by Saha et al. 2006. This methodology
demonstrates that CMB power spectrum can be reliably estimated solely from WMAP
data without assuming any template models for the foreground components. In the
current paper, we extend this work to estimate the galactic foreground power
spectrum using the WMAP 5 year maps following a self contained analysis. We
apply the model independent method in harmonic basis to estimate the foreground
power spectrum and frequency dependence of combined foregrounds. We also study
the behaviour of synchrotron spectral index variation over different regions of
the sky. We compare our results with those obtained from MEM foreground maps
which are formed in pixel space. We find that relative to our model independent
estimates MEM maps overestimates the foreground power close to galactic plane
and underestimates it at high latitudes.Comment: 12 pages, 4 figure