Cleaned 3 year Wilkinson Microwave Anistropy Probe cosmic microwave background map:: Magnitude of the quadrupole and alignment of large-scale modes

We have produced a cleaned CMB temperature fluctuation map of the Wilkinson Microwave Anisotropy Probe (WMAP) 3 year data using an improved internal linear combination (ILC) method as a Galactic foreground subtraction technique. We divide the whole sky into hundreds of pixel groups with similar foreground spectral indices over a range of WMAP frequencies, apply the ILC for each group, and obtain a CMB map with foreground emission effectively reduced. With the resulting ILC map, we have investigated the known anomalies in CMB maps at large scales, namely, the low quadrupole (l = 2) power, and the strong alignment and planarity of the quadrupole and the octopole (l = 3). Our estimates are consistent with the previous measurements. The quadrupole and the octopole powers measured from our ILC map are delta T-2(2) = 276(-1236 mu)(+94)K(2) and delta T-3(2) = 952(-83)(+64) mu K-2, respectively. The 68% confidence limits are estimated from the ILC simulations and include the cosmic variance. The measured quadrupole power is lower than the value expected in the concordance Lambda CDM model (1250 mu K-2), in which the probability of finding a quadrupole power lower than the measured value is p = 5.7%. We have confirmed that the quadrupole and the octopole are strongly aligned with angle theta(23) = 11.8 degrees(+6.4)(- 8. 0 degrees) and are planar with high planarity parameters t = 0.98 +/- 0: 02 for l = 2 and t = 0.91(- 0.03)(+0.02) for l = 3. The observed angular separation theta(23) is marginally significant with p = 4: 3%. However, the observed planarity is not statistically significant. The probability of observing such a planarity as high as the measured t-values is over 18%. The ILC simulations show that the residual foreground emission in the ILCmap does not affect the estimated values significantly.