Preferred axis in cosmology

TL;DR

Recent cosmological observations suggest preferred directions in the universe that align with the CMB kinematic dipole, challenging the cosmological principle and indicating potential observational or local effects rather than fundamental physics.

Contribution

This paper identifies a common alignment of various cosmological anomalies with the CMB dipole, proposing a local or observational origin rather than a fundamental violation of cosmology.

Findings

Preferred axes in CMB parity violation, quadrupole, and octopole align with the CMB dipole.

Multiple cosmological anomalies are aligned with the CMB dipole.

The anomalies may be explained by local or observational systematics rather than new physics.

Abstract

The foundation of modern cosmology relies on the so-called cosmological principle which states an homogeneous and isotropic distribution of matter in the universe on large scales. However, recent observations, such as the temperature anisotropy of the cosmic microwave background (CMB) radiation, the motion of galaxies in the universe, the polarization of quasars and the acceleration of the cosmic expansion, indicate preferred directions in the sky. If these directions have a cosmological origin, the cosmological principle would be violated, and modern cosmology should be reconsidered. In this paper, by considering the preferred axis in the CMB parity violation, we find that it coincides with the preferred axes in CMB quadrupole and CMB octopole, and they all align with the direction of the CMB kinematic dipole. In addition, the preferred directions in the velocity flows, quasar alignment, anisotropy of the cosmic acceleration, the handedness of spiral galaxies, and the angular distribution of the fine-structure constant are also claimed to be aligned with the CMB kinematic dipole. Since CMB dipole was confirmed to be caused by the motion of our local group of galaxies relative to the reference frame of the CMB, the coincidence of all these preferred directions hints that these anomalies have a common origin, which is not cosmological or due to a gravitational effect. The systematical or contaminative errors in observation or in data analysis, which can be directly related to the motion of our local group of galaxies, can play an important role in explaining the anomalies.