Influence of Planck foreground masks in the large angular scale quadrant
  CMB asymmetry
  The measured CMB angular distribution shows a great consistency with the LCDM
model. However, isotropy violations were reported in CMB temperature maps of
both WMAP and Planck data. We investigate the influence of different masks
employed in the analysis of CMB angular distribution, in particular in the
excess of power in the Southeastern quadrant (SEQ) and the lack of power in the
Northeastern quadrant (NEQ). We compare the two-point correlation function
(TPCF) computed for each quadrant of the CMB foreground-cleaned temperature
maps to 1000 simulations generated assuming the LCDM best-fit power spectrum
using four different masks. In addition to the quadrants, we computed the TPCF
for circular regions in the map where the excess and lack of power are present.
We also compare the effect of Galactic cuts in the TPCF calculations as
compared to the simulations. We found consistent results for three masks,
namely mask-rulerminimal, U73 and U66. The results indicate that the excess of
power in the SEQ tends to vanish as the portion of the sky covered by the mask
increases and the lack of power in the NEQ remains virtually unchanged. When
UT78 mask is applied, the NEQ becomes no longer anomalous and the excess of
power in the SEQ becomes the most significant one among the masks.
Nevertheless, the asymmetry between the SEQ and NEQ is independent of the mask
and it is in disagreement with the isotropic model with at least 95% C.L. We
find that UT78 is in disagreement with the other analysed masks, specially
considering the SEQ and the NEQ individual analysis. Most importantly, the use
of UT78 washes out the anomaly in the NEQ. Furthermore, we found excess of
kurtosis, compared with simulations, in the NEQ for the regions not masked by
UT78 but masked by the other masks, indicating that the previous result could
be due to non-removed residual foregrounds by UT78.
