Galaxy Zoo: The large-scale spin statistics of spiral galaxies in the Sloan Digital Sky Survey

TL;DR

This study analyzes a large sample of spiral galaxy spins from SDSS to test for large-scale anisotropy, finding no significant preferred handedness and confirming the isotropy of the universe's spin distribution.

Contribution

It provides a corrected analysis of galaxy spin directions from Galaxy Zoo, demonstrating no evidence of large-scale anisotropy in the universe.

Findings

No significant dipole signal detected.

Galaxy spin distribution consistent with isotropy.

Bias correction crucial for accurate results.

Abstract

We re-examine the evidence for a violation of large-scale statistical isotropy in the distribution of projected spin vectors of spiral galaxies. We have a sample of $\sim 37,000$ spiral galaxies from the Sloan Digital Sky Survey, with their line of sight spin direction confidently classified by members of the public through the online project Galaxy Zoo. After establishing and correcting for a certain level of bias in our handedness results we find the winding sense of the galaxies to be consistent with statistical isotropy. In particular we find no significant dipole signal, and thus no evidence for overall preferred handedness of the Universe. We compare this result to those of other authors and conclude that these may also be affected and explained by a bias effect.