Explain the CMB hemispherical power asymmetry

Determine the physical origin of the observed hemispherical asymmetry in CMB power and assess whether it is physically connected to the reported hemispherical overdensity of early-type galaxies.

Background

The paper describes a reported correspondence between warmer, higher-power CMB regions and a sky region containing an excess of early-type galaxies. Although the paper suggests that the correlation could indicate a large-scale matter inhomogeneity, it does not establish the connection and identifies the CMB asymmetry as unresolved.

References

The CMB hemispherical power asymmetry is significant but not understood.

— The relevance of the cosmic microwave background for cosmology  (2609.10672 - Kroupa et al., 9 Sep 2026) in Section 4.3, “Hemispherical asymmetry”

It has to be verified if this deviation from anisotropy is consistent with the global anisotropy intrinsic to the $3-$torus multiply connected topology.

— The variance of the CMB temperature gradient: a dependence on the spatial orientation and anisotropy of a multiply connected Universe  (2610.12179 - Aurich et al., 8 Oct 2026) in Section 1, Introduction