author = "Santos, L. and Cabella, P. and Villela, Thyrso and Zhao, W.",
          affiliation = "{University of Sciences and Technology of China} and {Universita 
                         di Roma} and {Instituto Nacional de Pesquisas Espaciais (INPE)} 
                         and {Chinese Academy of Sciences}",
                title = "Influence of Planck foreground masks in the large angular scale 
                         quadrant CMB asymmetry",
              journal = "Astronomy and Astrophysics",
                 year = "2015",
               volume = "584",
               number = "A115",
                month = "Dec.",
             keywords = "Cosmic background radiation, Cosmology: observations, Methods: 
                         data analysis, Methods: statistical.",
             abstract = "The measured cosmic microwave background (CMB) angular 
                         distribution shows high consistency with the \ΛCDM model, 
                         which predicts cosmological isotropy as one of its fundamental 
                         characteristics. However, isotropy violations were reported in CMB 
                         temperature maps of the Wilkinson Microwave Anisotropy Probe 
                         (WMAP) and confirmed by Planck satellite data. Aims. Our purpose 
                         is to investigate the influence of different sky cuts (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), 
                         found in both WMAP and Planck data. Methods. We compared the 
                         two-point correlation function (TPCF) computed for each quadrant 
                         of the CMB foreground-cleaned temperature maps to 1000 Monte Carlo 
                         (MC) simulations generated assuming the \ΛCDM best-fit power 
                         spectrum using four different masks, from the least to the most 
                         severe one: mask-rulerminimal, UT78, U73, and U66. In addition to 
                         the quadrants and for a better understanding of these anomalies, 
                         we computed the TPCF using the mask-rulerminimal for circular 
                         regions in the map where the excess and lack of power are present. 
                         We also compared, for completeness, the effect of Galactic cuts 
                         (+/-10, 20, 25, and 30 degrees above/below the Galactic plane) in 
                         the TPCF calculations as compared to the MC simulations. Results. 
                         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. A different result arises for the 
                         newly released UT78 Planck mask. When this mask is applied, the 
                         NEQ is no longer anomalous. On the other hand, 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 disagrees with the isotropic model with at 
                         least 95% C.L. Conclusions. We find that UT78 disagrees with the 
                         other analyzed masks, especially when considering the SEQ and the 
                         NEQ individual analysis. Most important, the use of UT78 washes 
                         out the anomaly in the NEQ. Furthermore, we find an 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 unremoved residual foregrounds 
                         by UT78.",
                  doi = "10.1051/0004-6361/201526713",
                  url = "http://dx.doi.org/10.1051/0004-6361/201526713",
                 issn = "0004-6361 and 1432-0746",
             language = "en",
           targetfile = "santos.pdf",
        urlaccessdate = "29 nov. 2020"