Participatory horizons and the cosmic dipole anomaly

The observed dipole in extragalactic source number counts is approximately twice as large as the kinematic expectation derived from the CMB rest frame, a discrepancy that has persisted across radio, infrared, and mid-infrared catalogues and remained contested despite extensive investigation of local structure, masking, and survey-systematic effects. Most discussions treat the excess as evidence for an unknown source-side effect, a violation of the cosmological principle, or a statistical fluctuation. Here, we explore an observer-relative alternative motivated by Wheeler's participatory view of measurement. Building on companion analyses in which the observer's causal diamond was modelled as an information aperture (isotropic for the low-power anomaly, quadrupolar for the Axis of Evil) we extend the participatory-horizon framework to the dipolar (L = 1) sector of the recording kernel. In the additive formulation, the kernel's first Legendre mode couples to the dominant source-count monopole via Gaunt integrals, injecting a constant excess D_ = A into the observed dipole parallel to the observer's velocity, where A is an aperture amplification factor. Applied to the CatWISE2020 photometric quasar catalogue (\, 1. 36 million sources over \, 47\% of the sky), the pipeline yields A = 5. 3 1. 3 at the fiducial threshold (W1 16. 4\, mag), a 4. 0 excess above the kinematic-only model. The corresponding dipole gain is G = D_ / D₊₈₍ = 1. 86 0. 21; within the additive framework the full -projected excess is accounted for, reducing the \, 4 tension along the velocity axis to a single fitted parameter. A cumulative magnitude-threshold scan finds A stable over the high-purity range (W1 16. 1), with a mean of \, 6. 7, declining only where catalogue contamination is expected to dominate the sample; in contrast to the monotonic dilution predicted by local-structure models. A 30-configuration robustness grid confirms insensitivity to neighbour-buffer depth and ecliptic model, with the Galactic latitude cut as the dominant systematic. The transverse component D_ is small at bright thresholds and grows with catalogue depth, compatible with an on-axis additive excess from an axisymmetric kernel and a separate threshold-dependent contaminant. The framework makes a parameter-free cross-survey prediction that the absolute excess D_ should be common to all source populations, so that surveys with different Ellis--Baldwin prefactors should exhibit predictably different fractional excesses. Spectroscopic redshift slices from DESI and forthcoming surveys can test this directly, since a constant A across redshift bins would be difficult to explain by any source-side mechanism. Together with the companion analyses of the CMB power deficit (L=0) and the Axis-of-Evil alignment (L=2), these results extend the participatory recording kernel to a third anomaly channel, the source-count dipole tension, conventionally discussed outside the CMB large-angle literature. A single kernel W () =1+₁ P₁ () +₂ P₂ (), applied to a standard CDM background, can feasibly accommodate all three anomalies through successive Legendre sectors; several significant open problems are discussed.