  Significant alignment and signed-intensity anomalies of local features of the
cosmic microwave background (CMB) are detected on the three-year WMAP data,
through a decomposition of the signal with steerable wavelets on the sphere.
Firstly, an alignment analysis identifies two mean preferred planes in the sky,
both with normal axes close to the CMB dipole axis. The first plane is defined
by the directions toward which local CMB features are anomalously aligned. A
mean preferred axis is also identified in this plane, located very close to the
ecliptic poles axis. The second plane is defined by the directions anomalously
avoided by local CMB features. This alignment anomaly provides further insight
on recent results (Wiaux et al. 2006). Secondly, a signed-intensity analysis
identifies three mean preferred directions in the southern galactic hemisphere
with anomalously high or low temperature of local CMB features: a cold spot
essentially identified with a known cold spot (Vielva et al. 2004), a second
cold spot lying very close to the southern end of the CMB dipole axis, and a
hot spot lying close to the southern end of the ecliptic poles axis. In both
analyses, the anomalies are observed at wavelet scales corresponding to angular
sizes around 10 degress on the celestial sphere, with global significance
levels around 1%. Further investigation reveals that the alignment and
signed-intensity anomalies are only very partially related. Instrumental noise,
foreground emissions, as well as some form of other systematics, are strongly
rejected as possible origins of the detections. An explanation might still be
envisaged in terms of a global violation of the isotropy of the Universe,
inducing an intrinsic statistical anisotropy of the CMB.
