Large-Scale Asymmetry in the Distribution of Galaxy Spin Directions—Analysis and Reproduction

Abstract

Recent independent observations using several different telescope systems and analysis methods have provided evidence of parity violation between the numbers of galaxies that spin in opposite directions. On the other hand, other studies argue that no parity violation can be identified. This paper provides detailed analysis, statistical inference, and reproduction of previous reports that show no preferred spin direction. Code and data used for the reproduction are publicly available. The results show that the data used in all of these studies agree with the observation of a preferred direction as observed from Earth. In some of these studies, the datasets were too small, or the statistical analysis was incomplete. In other papers, the results were impacted by experimental design decisions that led directly to showing nonpreferred direction. In some of these cases, these decisions were not stated in the papers but were revealed after further investigation in cases where the reproduction of the work did not match the results reported in the papers. These results show that the data used in all of these previous studies, in fact, agree with the contention that galaxies as observed from Earth have a preferred spin direction, and the distribution of galaxy spin directions as observed from Earth forms a cosmological-scale dipole axis. This study also shows that the reason for the observations is not necessarily an anomaly in the large-scale structure, and can also be related to internal structure of galaxies.

Galaxy spin direction asymmetry in JWST deep fields

“…Similarly, 6.032% were annotated as rotating counterclockwise in the original images, compared to just 5.942% of the galaxies that were annotated as rotating counterclockwise in the mirrored images, showing that 1.5% more galaxies rotate counterclockwise. As explained in Shamir (2023, the 1.5%-2.2% asymmetry is in excellent agreement with the asymmetry reported in Shamir (2020d), which was analysed using the same footprint of SDSS galaxies with Table 2 The number of galaxies rotating in opposite directions in the original and mirrored images used in Land et al (2008).…”

“…More importantly, as discussed in detail in Shamir (2023), reproducing the experiment with the same data and same analysis described in Iye et al (2021) provides completely different results than the results shown by Iye et al (2021). Figure 11 shows the outcome of the experiment, showing a statistically significant dipole axis of 2.14σ formed by the galaxy spin directions.…”

“…Analysis and reproduction of all of these experiments showed that the data on which these reports are based is in fact in agreement with non-random distribution (Shamir, 2023). The analysis and reproduction, including the code and data to reproduce the experiments, are described in detail in Shamir (2023; ; Shamir (2022a), and will be explained briefly also in Section 4 of this paper.…”

“…redshift. When combining the P values of the two experiments, the asymmetry becomes statistically significant (Shamir, 2023. Table 2 in this paper shows the number of galaxies that rotate in opposite directions used in the two experiments described by Land et al (2008) when the galaxy images were mirrored to offset for the human bias.…”

“…Another experiment (Hayes et al, 2017) that used SDSS galaxies with redshift used computer analysis to annotate the direction of rotation of the galaxies that were annotated manually by Land et al (2008). That experiment is analysed and reproduced in , and discussed also in Shamir (2023). As shown by Table 2 in Hayes et al (2017), the analysis showed a higher number of galaxies rotating counterclockwise, with statistical significance of between 2σ to 3σ.…”