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arXiv 1701.08583astro-ph.CO
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部分与整体:空洞、超级空洞及其ISW印记

The part and the whole: voids, supervoids, and their ISW imprint

András Kovács

摘要:

宇宙网中极端结构的综合萨克斯-沃尔夫印记探索了暗能量的动力学本质。透过典型的宇宙空洞观察,没有异常信号的报道。相反,与引力势的大尺度波动相关的超级空洞,已经显示出潜在的干扰过量信号。在这项研究中,我们使用的Jubilee ISW模拟,以证明如何堆叠的信号取决于空洞的定义。我们发现,大的欠密度,至少有$\approx5$合并的子空洞,显示出一个特殊的ISW印记形状与中央冷点和周围的热环,提供了一个自然的方式来定义宇宙网络中的超级空洞。然后,我们使用模拟印记作为模板检查了真实世界的BOSS DR 12数据。BOSS超空穴的印迹轮廓似乎比模拟中更紧凑,需要额外的$α\approx 0.7$重新缩放过滤器尺寸。数据显示,在$\approx2.5σ$显著性水平下,$A_{\rm ISW}\approx9$振幅的ISW样信号过多,这与先前使用孤立空隙并报告与$A_{\rm ISW}=1$具有良好一致性的研究不同。基于朱比利的$Λ$ CDM预测的张力是$\sim 2σ$,与暗能量调查数据中对超级空洞的独立分析一致。我们发现,这样一个非常大的增强的$A_{\rm ISW}$参数暗示在CMB冷点和波江座超空之间的可能的因果关系。这些发现的起源尚不清楚。

英文摘要:

The integrated Sachs-Wolfe imprint of extreme structures in the cosmic web probes the dynamical nature of dark energy. Looking through typical cosmic voids, no anomalous signal has been reported. On the contrary, supervoids, associated with large-scale fluctuations in the gravitational potential, have shown potentially disturbing excess signals. In this study, we used the Jubilee ISW simulation to demonstrate how the stacked signal depends on the void definition. We found that large underdensities, with at least $\approx5$ merged sub-voids, show a peculiar ISW imprint shape with central cold spots and surrounding hot rings, offering a natural way to define supervoids in the cosmic web. We then inspected the real-world BOSS DR12 data using the simulated imprints as templates. The imprinted profile of BOSS supervoids appears to be more compact than in simulations, requiring an extra $α\approx 0.7$ re-scaling of filter sizes. The data reveals an excess ISW-like signal with $A_{\rm ISW}\approx9$ amplitude at the $\approx2.5σ$ significance level, unlike previous studies that used isolated voids and reported good consistency with $A_{\rm ISW}=1$. The tension with the Jubilee-based $Λ$CDM predictions is $\sim 2σ$, in consistency with independent analyses of supervoids in Dark Energy Survey data. We show that such a very large enhancement of the $A_{\rm ISW}$ parameter hints at a possible causal relation between the CMB Cold Spot and the Eridanus supervoid. The origin of these findings remains unclear.

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