Hemisphere-dependent power asymmetry,
Suppressed quadrupole amplitude, which challenge the assumption of statistical isotropy embedded in CDM.
In a Bianchi IX universe with decaying vorticity:
Vorticity-induced frame dragging introduces anisotropic redshift patterns in the last scattering surface,
Residual shear modulates the Sachs--Wolfe effect and alters angular correlation functions,
Alignment of multipoles arises naturally from coherent rotation seeded by primordial torsion.
Quantitatively, the perturbed CMB temperature anisotropies take the modified form:
TT(n^)=(TT)iso+(TT)vort+(TT)shear,\frac{\Delta T}{T}(\hat{n}) = \left( \frac{\Delta T}{T} \right)_{\text{iso}} + \left( \frac{\Delta T}{T} \right)_{\text{vort}} + \left( \frac{\Delta T}{T} \right)_{\text{shear}},
with the additional terms encoding preferred directions and angular momentum signatures. These perturbations could account for the observed alignment of low-\ell modes without invoking non-standard inflation.
5.2 Impacts on BAO and Supernova Constraints
Baryon Acoustic Oscillations (BAO) and Type Ia supernovae provide critical constraints on the expansion history and spatial geometry of the universe. In torsion-driven Bianchi IX cosmology:
