Symmetry in Hyper Suprime-Cam galaxy spin directions

Abstract

We perform a Bayesian analysis of anisotropy in binary galaxy spin directions in the Hyper-Suprime Cam Data Release 3 catalogue, in response to a recent claim that it exhibits a dipole (Shamir 2024). We find no significant evidence for anisotropy, or for a direction-independent spin probability that differs from 0.5. These results are unchanged allowing for a quadrupole or simply searching for a fixed anisotropy between any two hemispheres, and the Bayes factor indicates decisive evidence for the isotropic model. Our principled method contrasts with the statistic employed by Shamir 2024, which lacks a strong theoretical foundation.

3 pages, 1 figure. Accepted in RNAAS

References in corpus (6)

• Third Data Release of the Hyper Suprime-Cam Subaru Strategic Program
• A Challenge to the Standard Cosmological Model
• Detection of a Dipole in the Handedness of Spiral Galaxies with Redshifts z ~ 0.04
• Analyzing the Large-Scale Bulk Flow using CosmicFlows4: Increasing Tension with the Standard Cosmological Model
• Reanalysis of the spin direction distribution of Galaxy Zoo SDSS spiral galaxies
• No evidence for anisotropy in galaxy spin directions