Radio Axis Alignments

Radio galaxies and quasars exhibit a tendency for their radio jet axes — which are set by the spin axis of the central supermassive black hole — to be aligned with each other across scales of hundreds of megaparsecs, well beyond the gravitational influence radius of any individual galaxy. Studies of large quasar samples have found statistically significant alignments of radio jet position angles over comoving scales of 500 Mpc or more, with alignment fractions exceeding the isotropic expectation at the three-sigma level or better. Standard ΛCDM structure formation, in which black hole spins are set by the angular momentum of infalling gas from random merger-driven accretion events, predicts no large-scale jet alignment — each black hole spin is expected to reflect only its local merger history. The observed alignment therefore requires either a physical mechanism that correlates black hole spins over hundreds of megaparsecs, or a new understanding of how spin orientations are set during galaxy formation.

Successive Collision Theory predicts large-scale radio jet alignment as a direct and inevitable consequence of angular momentum inheritance. The initial pocket collision deposited a global angular momentum vector J into the entire debris field with a preferred axis set by the collision geometry. Every structure that subsequently formed — including the supermassive black holes at galaxy centers — inherited angular momentum from this same global field, with the inherited component proportional to their mass and position within the debris stratum. The spin axes of SMBHs therefore reflect the local angular momentum direction in the debris field at their formation location, and since this field is coherent over scales set by the collision geometry (hundreds to thousands of megaparsecs), neighboring SMBHs that formed from adjacent debris strata have correlated spin orientations. The radio jet axis, being set by the SMBH spin, inherits this large-scale angular correlation directly.

The observed correlation length of ~500 Mpc for radio axis alignments matches the characteristic scale of the angular momentum coherence expected from the collision geometry in SCT — the scale over which the impact-parameter-determined angular momentum field varies by order unity. This scale is set by the effective sizes of the two colliding pockets and their relative impact parameter, and SCT predicts that it should also match the coherence scale of galaxy spin alignments, filament orientation correlations, and CMB quadrupole-octupole alignment, since all these phenomena trace the same underlying angular momentum field. The convergence of all these alignment scales on the same characteristic length is a powerful consistency test of the angular momentum inheritance framework.