arXiv 2004.144352020-04astro-ph.CO

用普朗克数据检验大爆炸前事件的径向导数

Radial derivatives as a test of pre-Big-Bang events on the Planck data

R. Fernández-Cobos, A. Marcos-Caballero, E. Martínez-González

备注：: 8 figures, 4 tables
DOI：: 10.1093/mnras/staa2844

摘要：

虽然在宇宙学巡天中寻找方位角模式对于解释某些只依赖于标准模型中的角距离的效应是有用的，但它们被认为是某些奇异场景的关键区别特征，例如气泡碰撞或共形循环宇宙学（CCC）。特别是，CCC是一个非标准的框架，预测CMB强度波动的圆形图案。出于以前的一些作品，探索径向梯度的存在下，我们应用的径向导数的基础上，最新发布的\textit{Planck}数据的方法。新方法允许以$N_{\mathrm{side}} = 1024$的HEALPix分辨率在所有天空方向进行详尽的研究。具体而言，两个不同的分析进行集中在小（高达$5$度半径）和大规模的权重函数。我们将我们的结果与An et al.（2017）和An et al.（2018）的结果进行了比较。此外，一个可能的偏振对应这些圆形图案也分析了最有前途的情况下。考虑到表征结果的意义的局限性，包括遭受“别处看”效应的可能性，在小尺度或大尺度的\textit{Planck}数据中没有发现CCC预期的圆形模式的有力证据。

英文摘要：

Although the search for azimutal patterns in cosmological surveys is useful to characterise some effects depending exclusively on an angular distance within the standard model, they are considered as a key distinguishing feature of some exotic scenarios, such as bubble collisions or conformal cyclic cosmology (CCC). In particular, the CCC is a non-stardard framework which predicts circular patterns on the CMB intensity fluctuations. Motivated by some previous works which explore the presence of radial gradients, we apply a methodology based on the radial derivatives to the latest release of \textit{Planck} data. The new approach allows exhaustive studies to be performed at all sky directions at a HEALPix resolution of $N_{\mathrm{side}} = 1024$. Specifically, two different analyses are performed focusing on weight functions in both small (up to a $5$-degree radius) and large scales. We present a comparison between our results and those shown by An et al. (2017), and An et al. (2018). In addition, a possible polarization counterpart of these circular patterns is also analysed for the most promising case. Taking into account the limitations to characterize the significance of the results, including the possibility of suffering a look-elsewhere effect, no strong evidence of the kind of circular patterns expected from CCC is found in the \textit{Planck} data for either the small or the large scales.

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