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Large-scale asymmetry in galaxy spin directions — Results from the Dark Energy Survey and comparison to four other sky surveys

Presentation #202.05 in the session Cosmology — iPoster Session.

Published onJun 29, 2022
Large-scale asymmetry in galaxy spin directions — Results from the Dark Energy Survey and comparison to four other sky surveys

Observations using large datasets of galaxies imaged by DECam, SDSS, HST, and Pan-STARRS have shown substantial evidence of non-random cosmological-scale patterns in the spin directions of spiral galaxies. Here a dataset of nearly 800K galaxies imaged by the Dark Energy Survey are annotated by their spin directions. The results show patterns of non-random distribution of spiral galaxies. A chi2 cosine dependence analysis shows a Hubble-scale dipole axis with statistical significance of 3.7 σ. The profile of the spin directions of spiral galaxies and the location of the dipole axis is in very close agreement with the profiles observed by Pan-STARRS, DECam, and SDSS, and is well within one σ from the dipole axis observed using HST data. All sky surveys show very similar patterns of non-random distribution of galaxy spin directions, and exhibit a Hubble-scale axis at the same location. That axis agrees across eight additional datasets of galaxies annotated by their spin directions. Some of the smaller datasets were annotated manually, while the larger datasets were annotated automatically by applying a fully symmetric model-based algorithm that follows clear symmetric rules. In all cases the results are nearly identical, further demonstrating the consistency of the patterns. The change in the strength and location of the most likely axis when the redshift of the galaxies gets higher suggests that if such axis indeed exists, it might not go directly through Earth. Possible errors that can lead to the observation are discussed, and previous studies showing opposite results are analyzed to understand the experimental design that led to the observations.

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