The small scale power asymmetry in the cosmic microwave background

Understand

We investigate the hemispherical power asymmetry in the cosmic microwave background on small angular scales.

• We find an anomalously high asymmetry in the multipole range l=601-2048, with a naive statistical significance of 6.5 sigma.
• However, we show that this extreme anomaly is simply a coincidence of three other effects, relativistic power modulation, edge effects from the mask applied, and inter-scale correlations.
• After correcting for all of these effects, the significance level drops to ~1 sigma, i.e., there is no anomalous intrinsic asymmetry in the small angular scales.