Increasing evidence for hemispherical power asymmetry in the five-year WMAP data

Understand

(Abridged)Motivated by the recent results of Hansen et al.

• (2008) concerning a noticeable hemispherical power asymmetry in the WMAP data on small angular scales, we revisit the dipole modulated signal model introduced by Gordon et al.
• (2005).
• This model assumes that the true CMB signal consists of a Gaussian isotropic random field modulated by a dipole, and is characterized by an overall modulation amplitude, A, and a preferred direction, p.