Using CMB polarization to constrain the anomalous nature of the Cold
  Spot with an incomplete sky-coverage
  Recent results of the ESA Planck satellite have confirmed the existence of
some anomalies in the statistical distribution of the cosmic microwave
background (CMB) anisotropies. One of the most intriguing anomalies is the Cold
Spot, firstly detected in the WMAP data by Vielva et al. (2004). In a later
paper, Vielva et al. (2011) developed a method to probe the anomalous nature of
the Cold Spot by using the cross-correlation of temperature and polarization of
the CMB fluctuations. Whereas this work was built under the assumption of
analysing full-sky data, in the present paper we extend such approach to deal
with realistic data sets with a partial sky-coverage. In particular, we exploit
the radial and tangential polarization patterns around temperature spots. We
explore the capacity of the method to distinguish between a standard Gaussian
CMB scenario and an alternative one, in which the Cold Spot arises from a
physical process that does not present correlated polarization features (e.g.,
topological defects), as a function of the instrumental-noise level. Moreover,
we consider more in detail the case of an ideal noise-free experiment and those
ones with the expected instrumental-noise levels in QUIJOTE and Planck
experiments. We also present an application to the 9-year WMAP data, without
being able to obtain firm conclusions, with a significance level of 32%. In the
ideal case, the alternative scenario could be rejected at a significance level
of around 1%, whereas for expected noise levels of QUIJOTE and Planck
experiments the corresponding significance levels are 1.5% and 7.4%,
respectively.
