COSMO
In the literature: open
Is the hemispherical power asymmetry a real dipolar modulation?
In plain words
One half of the microwave sky shows slightly stronger fluctuations than the other half on large scales. If real, it would mean the universe is not the same in all directions.
Precise statement
Planck temperature data show a dipolar modulation $\Delta T \to (1 + A n.p) \Delta T$ with amplitude $A \sim 0.07$ for multipoles $\ell$ up to $\sim 64$ (moderate confidence on the exact value). Determine whether the modulation is present in polarization and in large-scale structure with the amplitude and direction expected for a physical modulation, or absent.
What would settle it
Detection or exclusion of the same modulation in large-angle E-modes and in tomographic galaxy and lensing maps.
Related problems
- Special case of Are the CMB large-angle anomalies statistical flukes or physics?