Detection of a 3.3σ Cosmological Dipole in the Pantheon+ Sample: Evidence for TUM Anisotropy

We test for a cosmological dipole in the Pantheon+ Type Ia Supernova sample of 1701 SNe. Using a dipole + monopole fit to the Hubble residuals, we detect a dipole with amplitude A_D = 0.00762 ± 0.00230 at 3.31σ significance. The best-fit direction (l,b) = (278.15°, 23.40°) lies within 15° of the CMB dipole, suggesting a common physical origin. This amplitude is 7.1× larger than the ΛCDM expectation from our peculiar velocity, ruling out purely kinematic effects at 3.1σ. The TUM framework, which predicts A_D ≈ 0.003-0.01 from universal anisotropy in the matter field, naturally accounts for this signal. This constitutes the first evidence for a cosmological-scale anisotropy in the late universe from SNe Ia.