  Several accurate analyses of the CMB temperature maps from the Wilkinson
Microwave Anisotropy Probe (WMAP) have revealed a set of anomalous results, at
large angular scales, that appears inconsistent with the statistical isotropy
expected in the concordance cosmological model $\Lambda$CDM. Because these
anomalies seem to indicate a preferred direction in the space, here we
investigate the signatures that a primordial magnetic field, possibly present
in the photon-baryon fluid during the decoupling era, could have produced in
the large-angle modes of the observed CMB temperature fluctuations maps. To
study these imprints we simulate Monte Carlo CMB maps, which are statistically
anisotropic due to the correlations between CMB multipoles induced by the
magnetic field. Our analyses reveal the presence of the North-South angular
correlations asymmetry phenomenon in these Monte Carlo maps, and we use these
information to establish the statistical significance of such phenomenon
observed in WMAP maps. Moreover, because a magnetic field produces planarity in
the low-order CMB multipoles, where the planes are perpendicular to the
preferred direction defined by the magnetic field, we investigate the
possibility that two CMB anomalous phenomena, namely the North-South asymmetry
and the quadrupole-octopole planes alignment, could have a common origin. Our
results, for large-angles, show that the correlations between low-order CMB
multipoles introduced by a sufficiently intense magnetic field, can reproduce
some of the large-angle anisotropic features mapped in WMAP data. We also
reconfirm, at more than 95% CL, the existence of a North-South power asymmetry
in the WMAP five-year data.
