Test of the Statistical Isotropy of the Universe using Gravitational Waves

Understand

Since WMAP and Planck some anomalous features appeared in the Cosmic Microwave Background (CMB) large-angle anisotropy, the so-called anomalies.

• One of these is the hemispherical power asymmetry, i.e.
• a difference in the average power on the two hemispheres centered around (l, b) = (221, -20), which shows a relatively high level of significance.
• Such an anomaly could be the signature of a departure from statistical isotropy on large scales.