Multipole alignment in the large-scale distribution of spin direction of spiral galaxies

Abstract: Previous observations have suggested non-random distribution of spin directions of galaxies at scales far larger than the size of a supercluster. Here I use $\sim1.7\cdot10^5$ spiral galaxies from SDSS and $3.3\cdot10^4$ spiral galaxies from Pan-STARRS to analyze the distribution of galaxy spin patterns of spiral galaxies as observed from Earth. The analysis shows in both SDSS and Pan-STARRS that the distribution of galaxy spin directions forms a non-random pattern, and can be fitted to a dipole axis in probability much higher than mere chance. These observations agree with previous findings, but are based on more data and two different telescopes. The analysis also shows that the distribution of galaxy spin directions fits a large-scale multipole alignment, with best fit to quadrupole alignment with probability of $\sim6.9\sigma$ to have such distribution by chance. Comparison of two separate datasets from SDSS and Pan-STARRS such that the galaxies in both datasets have similar redshift distribution provides nearly identical quadrupole patterns.

• The paper presents statistically significant evidence for large-scale multipole alignment in the spin directions of spiral galaxies, based on analysis of over 200,000 galaxies from SDSS and Pan-STARRS.
• Analysis revealed statistically significant dipole and particularly strong quadrupole alignment (over 6.9sigma) of galaxy spin axes, with the dipole axis aligning with previously reported CMB anisotropies.
• These findings challenge the assumption of universal isotropy on large scales, suggesting the need for potential extensions to cosmological models or further empirical investigation using future observational facilities.

An Analysis of Multipole Alignment in Galactic Spin Directions

The research paper titled "Multipole alignment in the large-scale distribution of spin direction of spiral galaxies" by Lior Shamir presents an empirical analysis of the spatial distribution of spin directions of spiral galaxies on cosmological scales. Utilizing data from the Sloan Digital Sky Survey (SDSS) and the Pan-STARRS telescope, this study builds upon previous work by extending the dataset to approximately 170,000 spiral galaxies from SDSS and over 33,000 from Pan-STARRS, thus enhancing the statistical rigour and robustness of the findings.

Summary of Findings and Methodology

The paper focuses on the anisotropic distribution of galaxy spin directions, exploring whether such distributions exhibit large-scale spatial patterns. The expectation under isotropy, a fundamental postulate of the standard cosmological model, is that the spin directions, given observational parity from Earth, should be random. Contrarily, this study provides statistically significant evidence suggesting otherwise.

Data Collection and Processing:

• The principal datasets involve spiral galaxies, classified by algorithms without human bias, ensuring consistent and scalable processing. Specifically, the Ganalyzer algorithm was employed, a deterministic and model-driven approach with a clear rule-based methodology that distinguishes between clockwise (CW) and counterclockwise (CCW) spin orientations by analyzing radial intensity plots of galactic images. This choice mitigates biases associated with the complex decision boundaries characteristic of neural networks.
• The datasets were cross-referenced to exclude biases that might stem from particular instrument idiosyncrasies of the telescopes utilized. Furthermore, comparisons between SDSS and Pan-STARRS reflect a high degree of consistency, reinforcing the validity of the findings.

Results and Implications:

• Analysis revealed that the distribution of galaxy spin directions fits a dipole pattern with greater probability than expected by chance, aligning broadly with the spin direction asymmetry previously reported in more limited observational datasets. More importantly, a quadrupole alignment emerges prominently, with statistical significance exceeding 6.9σ, implying a profound large-scale organization.
• The dipole axis with the highest statistical significance was identified at right ascension and declination coordinates that align with similar cosmological anisotropies reported in Cosmic Microwave Background (CMB) analyses.

Evaluative Perspective and Theoretical Implications

These findings present a potential challenge to the cosmological principle, suggesting that the universe might exhibit anisotropic properties on the largest scales. While previous studies have reported anomalies or "axes of evil," such as the ones identified in the CMB alignment studies, this paper contributes robust empirical evidence from extragalactic observations, adding a new dimension to the ongoing discourse on universal isotropy.

Crucially, these observations do not inherently violate known cosmological models; instead, they may provide insights into possible extensions or modifications of these theories. Potential explanations may involve primordial chiral asymmetries or rotation on a cosmological scale, hypotheses that warrant further theoretical and empirical exploration. With the advent of more advanced observation technologies, such as the Euclid Satellite or the Rubin Observatory, we can anticipate more nuanced scrutiny and verification of these large-scale anisotropic features.

Future Directions

The implications of such findings necessitate rigorous follow-up investigations to further delineate the scale and potential causes of the observed anisotropy. Extending the dataset across additional spectral bands, improving resolution, and cross-validating with ongoing radio and IR observations will be pivotal. Furthermore, exploring connections with other cosmological asymmetry measures, such as polarization and redshift space distortions, could provide holistic insights into the fundamental architecture of the universe.

In conclusion, while the study grounds its analysis in extensive datasets and robust methodologies, the broader cosmological significance remains contingent upon further empirical corroboration and theoretical integration.