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arXiv 1811.00537astro-ph.CO
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声音不和谐：基于经典距离阶梯和$Λ$ CDM的宇宙学声音视界的确定

Sounds Discordant: Classical Distance Ladder & $Λ$CDM -based Determinations of the Cosmological Sound Horizon

Kevin Aylor, Mackenzie Joy, Lloyd Knox, Marius Millea, Srinivasan Raghunathan, W. L. Kimmy Wu

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12 pages, 3 figures, published in ApJ
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摘要：

Ia型超新星，经典的距离阶梯方法校准，可以使用，结合星系调查两点关联函数，以经验确定的声音地平线$r_{\rm s}$的大小。$Λ$ CDM模型的假设，连同约束其参数的数据，也可用于确定声音水平线的大小。使用各种宇宙微波背景（CMB）的数据集来约束$Λ$ CDM参数，我们发现基于模型的声音地平线要大于实验确定的一个与2和3之间的统计显着性$σ$，取决于数据集。如果和解需要改变宇宙学模型，我们认为，变化可能是重要的，在20年的尺度因子进化重组之前。因此，未来的CMB观测可能能够测试任何此类调整;例如，像SPT-3G这样的第三代CMB勘测可以在扩展以允许附加的光自由度的$Λ$ CDM模型中实现对$r_{\rm s}$的约束的三倍改进。

英文摘要：

Type Ia Supernovae, calibrated by classical distance ladder methods, can be used, in conjunction with galaxy survey two-point correlation functions, to empirically determine the size of the sound horizon $r_{\rm s}$. Assumption of the $Λ$CDM model, together with data to constrain its parameters, can also be used to determine the size of the sound horizon. Using a variety of cosmic microwave background (CMB) datasets to constrain $Λ$CDM parameters, we find the model-based sound horizon to be larger than the empirically-determined one with a statistical significance of between 2 and 3$σ$, depending on the dataset. If reconciliation requires a change to the cosmological model, we argue that change is likely to be important in the two decades of scale factor evolution prior to recombination. Future CMB observations will therefore likely be able to test any such adjustments; e.g., a third generation CMB survey like SPT-3G can achieve a three-fold improvement in the constraints on $r_{\rm s}$ in the $Λ$CDM model extended to allow additional light degrees of freedom.

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