论文标题
天空上的巨大弧线
A Giant Arc on the Sky
论文作者
论文摘要
我们介绍了$ z \ sim 0.8 $的偶然发现“天空上的巨型弧”。巨型弧（GA）跨越$ \ sim 1 $ gpc（适当的尺寸，现在的时代），在天空上似乎几乎是对称的。它是通过使用Zhu \＆Ménard的目录中的，在背景类星体光谱中的中间MGII吸收器中发现的。 MGII吸收器的使用代表了一种新的方法，用于调查大型结构（LSSS），以$ 0.45 \ Lessim Z \ Lessim 2.25 $。我们介绍了GA的观察性属性，并使用基于以下方法的方法对其进行统计评估：（i）单链分层聚类（$ \ sim4.5σ$）; （ii）Cuzick-Edwards测试（$ \ sim3.0σ$）; （iii）功率谱分析（$ \ sim4.8σ$）。这些方法中的每一个都有独特的属性和力量，我们建议考虑合奏的证据。我们讨论了缓解发现后分析意义的任何{\ it hoc}方面的方法。 GA的过度密度为$Δρ/ρ\ sim 1.3 \ pm 0.3 $。 GA是最新的，也是最大的一组非常大的LSS集合，这些LSS可能（谨慎地）挑战宇宙学原理，建立了宇宙学的“标准模型”。可以想象，GA是Sloan Great Wall之类的结构的前体（但GA大约是大小的两倍），当宇宙大约是其当今年龄的一半时。
We present the serendipitous discovery of a `Giant Arc on the Sky' at $z \sim 0.8$. The Giant Arc (GA) spans $\sim 1$ Gpc (proper size, present epoch), and appears to be almost symmetrical on the sky. It was discovered via intervening MgII absorbers in the spectra of background quasars, using the catalogues of Zhu \& Ménard. The use of MgII absorbers represents a new approach to the investigation of large-scale structures (LSSs) at redshifts $0.45 \lesssim z \lesssim 2.25$. We present the observational properties of the GA, and we assess it statistically using methods based on: (i) single-linkage hierarchical clustering ($\sim 4.5σ$); (ii) the Cuzick-Edwards test ($\sim 3.0σ$); and (iii) power spectrum analysis ($\sim 4.8σ$). Each of these methods has distinctive attributes and powers, and we advise considering the evidence from the ensemble. We discuss our approaches to mitigating any {\it post-hoc} aspects of analysing significance after discovery. The overdensity of the GA is $δρ/ ρ\sim 1.3 \pm 0.3$. The GA is the newest and one of the largest of a steadily accumulating set of very large LSSs that may (cautiously) challenge the Cosmological Principle, upon which the `standard model' of cosmology is founded. Conceivably, the GA is the precursor of a structure like the Sloan Great Wall (but the GA is about twice the size), seen when the Universe was about half its present age.
