论文标题
宇宙学可观察物的二阶变不变形式主义：对其规格不变性的完整验证
Second-order gauge-invariant formalism for the cosmological observables: Complete verification of their gauge-invariance
论文作者
论文摘要
考虑到所有相对论效应，我们开发了完全非线性的规格形式主义，用于描述宇宙学观察力，并呈现了与光传播和观测相关的二阶扰动表达，而无需选择仪表条件。我们首次通过比较了从两种独立方法的量规转换属性进行比较二阶表达式的有效性的完整验证：一种是根据公制扰动直接从其表达中获得的，而另一种从其非线性关系中获得的。宇宙学可观察物（例如星系聚类和光度距离）的表达式在观察到的位置下不变，并且在观察到的位置上不变。我们将结果与以前的工作进行比较，并讨论扰动表达的差异。在精确宇宙学时代及其在未来的应用中，我们的二阶不变形式主义构成了向前迈出的重要一步，将对超越力量谱并探测早期宇宙发挥至关重要的作用。
Accounting for all the relativistic effects, we have developed the fully nonlinear gauge-invariant formalism for describing the cosmological observables and presented the second-order perturbative expressions associated with light propagation and observations without choosing a gauge condition. For the first time, we have performed a complete verification of the validity of our second-order expressions by comparing their gauge-transformation properties from two independent methods: one directly obtained from their expressions in terms of metric perturbations and the other expected from their nonlinear relations. The expressions for the cosmological observables such as galaxy clustering and the luminosity distance are invariant under diffeomorphism and gauge-invariant at the observed position. We compare our results to the previous work and discuss the differences in the perturbative expressions. Our second-order gauge-invariant formalism constitutes a major step forward in the era of precision cosmology and its applications in the future will play a crucial role for going beyond the power spectrum and probing the early universe.
