Hints of New Physics for the Hubble Tension: Violation of Cosmological Principle

Discrepancy between the measurements of Hubble constant H0 from the cosmic microwave background and the local distance ladder is the most serious challenge to the standard ΛCDM model. Recent research has pointed out that it might be related with the violation of cosmological principle. Here, we investigate the impact of dipole–monopole correction on the constraints of H0 utilizing the dipole-fitting method based on the ΛCDM model and cosmography method. Our results show that the dipole–monopole correction can reduce the constraints of H0 from a larger value consistent with SH0ES results to a smaller value consistent with Planck results. This finding can effectively alleviate the Hubble tension. Through making redshift tomography and model-independent analyses, we confirm that our findings are independent of the redshift and cosmological model. In addition, the theoretical prediction of H(z)/(1 + z) reconstructed by the constraints of the ΛCDM model with the dipole correction is in agreement with baryon acoustic oscillation (BAO) measurements, including five Dark Energy Spectroscopic Instrument BAOs within the 1σ range except a data point at z = 0.51. Our research suggests that the Hubble tension originates from new physics beyond the standard ΛCDM model, which might lead to a violation of the cosmological principle.