Handedness asymmetry of spiral galaxies with z<0.3 shows cosmic parity violation and a dipole axis

TL;DR

This study analyzes a large galaxy dataset revealing significant handedness asymmetry and a dipole axis in the local universe, suggesting potential cosmic parity violation.

Contribution

It introduces an automated image transformation method for analyzing galaxy spin and provides strong statistical evidence for anisotropy in galaxy handedness.

Findings

Significant handedness asymmetry with P<5.8×10^-6

Identification of a dipole axis at RA=132°, DEC=32°

Asymmetry amplitude aligns with previous studies but with higher significance

Abstract

A dataset of 126,501 spiral galaxies taken from Sloan Digital Sky Survey was used to analyze the large-scale galaxy handedness in different regions of the local universe. The analysis was automated by using a transformation of the galaxy images to their radial intensity plots, which allows automatic analysis of the galaxy spin and can therefore be used to analyze a large galaxy dataset. The results show that the local universe (z<0.3) is not isotropic in terms of galaxy spin, with probability P<5.8*10^-6 of such asymmetry to occur by chance. The handedness asymmetries exhibit an approximate cosine dependence, and the most likely dipole axis was found at RA=132, DEC=32 with 1 sigma error range of 107 to 179 degrees for the RA. The probability of such axis to occur by chance is P<1.95*10^-5 . The amplitude of the handedness asymmetry reported in this paper is generally in agreement with Longo, but the statistical significance is improved by a factor of 40, and the direction of the axis disagrees somewhat.