Large-scale Asymmetry Of Galaxy Spin Directions — A Comparison Of 12 Datasets

Several previous studies have suggested that the distribution of galaxy spin directions is not fully random, and exhibits patterns of asymmetry at cosmological scales. Here I compare 12 different datasets of spiral galaxies sorted by their spin directions. Analysis of the large-scale distribution of galaxy spin directions in each of the datasets shows large-scale dipole axes at different levels of statistical signal. While the direction of the most likely axis is somewhat different in different datasets, datasets with similar redshift distribution of the galaxies show similar directions of the dipole axes. Moreover, the change in the direction of the axis correlates with the changes in the mean redshift of the galaxies in each dataset. The datasets were collected by four different instruments: SDSS, Pan-STARRS, HST, and DECam. The galaxies in each dataset were classified by their spin directions either manually or automatically. The different datasets show similar distribution and similar location of the most likely dipole axis in similar redshift ranges. The datasets also show a correlation between the direction of the dipole axis and the mean redshift of the galaxies.