标题： 螺旋星系的自旋宇称 III -- 基于三维随机游走模拟的SDSS螺旋星系分布偶极子分析 显示英文标题

标题： Spin Parity of Spiral Galaxies III -- Dipole Analysis of the Distribution of SDSS Spirals with 3D Random Walk Simulations

摘要： 观测尚未确定星系自旋矢量的分布是否真正随机。尚不清楚宇宙中涡度场分布是否存在任何大规模的对称性破缺。 在这里，我们提出了一种方法来评估观测到的自旋分布的偶极分量 D_{最大}，其统计显著性 σ_{D}可以通过三维随机游走（随机飞行）模拟的预期幅度进行校准。我们将此方法应用于评估斯隆数字巡天（SDSS）螺旋星系分布中的偶极分量。 Shamir（2017a）发布了来自SDSS DR8的螺旋星系目录，并使用他的模式识别工具将其分类为顺时针和逆时针（分别对应Z-螺旋和S-螺旋）。他发现它们的分布存在显著的光度不对称性。我们已经确认，该样本提供了高达 σ_{D}= 4.00的偶极不对称性。然而，我们也发现目录中包含大量相同星系的重复条目。删除重复条目后，样本数量大幅减少至原来的45%。对于“清理”后的目录，实际观察到的偶极不对称性非常微弱，σ_{D}= 0.29。 我们得出结论，仅凭SDSS数据不足以支持局域宇宙中星系自旋矢量分布存在大规模对称性破缺的观点。数据与随机分布一致。 显示英文摘要

摘要： Observation has not yet determined whether the distribution of spin vectors of galaxies is truly random. It is unclear whether is there any large-scale symmetry-breaking in the distribution of the vorticity field in the universe. Here, we present a formulation to evaluate the dipole component D_{max} of the observed spin distribution, whose statistical significance sigma_{D} can be calibrated by the expected amplitude for 3D random walk (random flight) simulations. We apply this formulation to evaluate the dipole component in the distribution of Sloan Digital Sky Survey (SDSS) spirals. Shamir(2017a) published a catalog of spiral galaxies from the SDSS DR8, classifying them with his pattern recognition tool into clockwise and counterclockwise (Z-spiral and S-spirals, respectively). He found significant photometric asymmetry in their distribution. We have confirmed that this sample provides dipole asymmetry up to a level of sigma_{D}=4.00. However, we also found that the catalog contains a significant number of multiple entries of the same galaxies. After removing the duplicated entries, the number of samples shrunk considerably to 45%. The actual dipole asymmetry observed for the 'cleaned' catalog is quite modest, sigma_{D}=0.29. We conclude that SDSS data alone does not support the presence of a large-scale symmetry-breaking in the spin vector distribution of galaxies in the local universe. The data are compatible with a random distribution.