[论文解读] Is there a violation of the Copernican principle in radio sky

Ashok K. Singal|arXiv (Cornell University)|May 17, 2013

Scientific Research and Discoveries被引用 1

一句话总结

本文识别出3CRR巡天中强大宽线类星体和射电星系在天球分布中的显著大尺度各向异性，其中48个类星体中有33个集中在与地球自转和公转轴对齐的平面的一侧。此类不对称性随机发生的概率仅为约1%，挑战了哥白尼原理，并暗示宇宙中可能存在大尺度非均匀性或优选方向。

ABSTRACT

We report the presence of large anisotropies in the sky distributions of powerful extended quasars as well as some other sub-classes of radio galaxies in the 3CRR survey, the most reliable and most intensively studied complete sample of strong steep-spectrum radio sources. The anisotropies lie about a plane passing through the equinoxes and the north celestial pole. Out of a total of 48 quasars in the sample, 33 of them lie in one half of the observed sky and the remaining 15 in the other half. The probability that in a random distribution of 3CRR quasars in the sky, statistical fluctuations could give rise to an asymmetry in observed numbers up to this level is only $\sim 1\%$. Also only about 1/4th of Fanaroff-Riley 1 (FR1) type of radio galaxies lie in the first half of the observed sky and the remainder in the second half. If we include all the observed asymmetries in the sky distributions of quasars and radio galaxies in the 3CRR sample, the probability of their occurrence by a chance combination reduces to $\sim 2 imes 10^{-5}$. Two pertinent but disturbing questions that could be raised here are -- firstly why should there be such large anisotropies present in the sky distribution of some of the strongest and most distant discrete sources, implying inhomogeneities in the universe at very large scales (covering a fraction of the universe)? Secondly why should such anisotropies lie about a great circle decided purely by the orientation of earth's rotation axis and/or the axis of its revolution around the sun? Are these alignments a mere coincidence or do they imply that these axes have a preferential placement in the larger scheme of things, implying an apparent breakdown of the Copernican principle or its more generalization, cosmological principle, upon which the standard cosmological model is based upon?

研究动机与目标

• 调查3CRR巡天中强大射电源在天球分布中是否存在大尺度各向异性。
• 评估这些各向异性是否具有统计显著性，或可能源于随机涨落。
• 评估这些各向异性与地球自转和公转轴对齐是否暗示了宇宙学原理的破坏。
• 探讨此类对齐对基于哥白尼原理的标准宇宙学模型假设的影响。

提出的方法

• 分析了3CRR巡天中48个类星体和FR1型射电星系在天球上的空间分布。
• 定义了一个通过分点和北天极的参考平面，以检验是否存在不对称性。
• 计算在随机分布模型下观察到此类类星体计数不平衡（33比15）的概率。
• 评估在不同源类型中观察到的多种不对称性组合的联合概率。
• 使用统计显著性检验评估观察到的聚集是否可能由偶然引起。
• 评估与地球自转和公转轴对齐作为优选方向潜在指标的可能性。

实验结果

研究问题

• RQ1 在3CRR巡天中，强大宽线类星体在天球分布中是否存在显著的大尺度各向异性？
• RQ2 此类各向异性由随机天空分布中的统计涨落引起的概率是多少？
• RQ3 为何这些各向异性与地球自转和公转轴所定义的平面相一致？
• RQ4 这些对齐是否可能表明哥白尼原理或宇宙学原理遭到破坏？
• RQ5 这些发现是否挑战了标准宇宙学模型的基础假设？

主要发现

• 在3CRR样本中，48个类星体中有33个位于由分点和北天极定义的半球内，表明存在显著的不对称性。
• 此类类星体计数不平衡由随机原因引起的概率仅为约1%，表明具有统计显著性。
• 对于FR1型射电星系，约四分之一位于第一半球，其余位于第二半球，显示出类似的定向偏差。
• 当将类星体和射电星系中观察到的所有不对称性组合起来时，随机发生的概率降至约2×10⁻⁵。
• 各向异性与地球自转和公转轴对齐，引发了对宇宙学原理可能被破坏的担忧。
• 研究结果表明宇宙中可能存在大尺度非均匀性或优选方向，挑战了宇宙大尺度各向同性的假设。