无宇宙学原理的宇宙学：背景宇宙中的大尺度结构效应研究
Cosmology without the cosmological principle: A study of the large-scale structure effects in the background universe
AI总结：
该论文研究放宽ΛCDM模型的宇宙学原理假设，探索非均匀各向同性等宇宙模型，结合Ia型超新星等数据约束关键参数，为解决宇宙学危机提供新方向。
AI中文摘要：
近期研究强烈表明，鉴于不同宇宙学观测量之间日益加剧的张力，ΛCDM模型可能不再是宇宙学中明确的标准模型，一些研究者将这种情况描述为“宇宙学危机”。ΛCDM模型依赖两个基本假设：宇宙的各向同性（有观测证据支持）和哥白尼原理（一种哲学假设），这些假设共同导出了著名的宇宙学原理，而宇宙的均匀性正是其直接结果。在本论文中，作者回顾了放宽部分此类假设的宇宙学后果，研究了非均匀且各向同性的宇宙模型，以及考虑观察者相对于哈勃流运动的倾斜宇宙学。作者探讨了利用现有宇宙学数据研究这些效应的方法：首先，探索了描述非均匀且各向同性宇宙的多种模型，包括不同的度规理论、微扰分析、平均效应、倾斜场景以及宇宙学方法；随后，将该理论框架应用于Ia型超新星（SNIa）数据和本动速度场的分析，旨在约束关键参数。
英文摘要：
Recent studies strongly suggest that the $Λ$CDM model may no longer serve as the definitive standard model in cosmology, given the increasing tensions between different cosmological observables. Some researchers have described this situation as a "crisis in cosmology." The $Λ$CDM model relies on two fundamental assumptions: the isotropy of the universe (supported by observational evidence) and the Copernican principle (a philosophical postulate). Together, these assumptions lead to the well-known Cosmological Principle, with the homogeneity of the universe emerging as a direct consequence. In this thesis, I review the cosmological consequences of relaxing some of these assumptions, exploring inhomogeneous and anisotropic universe models, as well as tilted cosmologies, which consider observers in motion relative to the Hubble flow. We examine methods to study these effects using existing cosmological data. First, we explore a variety of models that describe inhomogeneous and anisotropic universes, including different metric theories, perturbative analyses, averaging effects, tilted scenarios, and cosmographic approaches. We then apply this theoretical framework to analyze SNIA data and the local peculiar velocity field, aiming to constrain key parameters.
