Perturbations and observables in inhomogeneous cosmologies

有没有可能，宇宙的明显加速膨胀不是由于暗能量的排斥作用，而是由一个巨大的、低密度的局部环境的行为所模仿的？这个问题经常被提及。广义相对论的lema<s:1> trer - tolman - bondi （LTB）解类提供了一个特别合适的理想框架。迄今为止在这种背景下取得的结果似乎表明，最近的宇宙学数据排除了在某些限制性假设下我们可能生活在非均匀宇宙中的假设，但与更自由条件下的LTB解释并不冲突。我们建议以五种方式扩展现有的研究。我们将从LTB类中选择那些具有同步大爆炸的模型。在此基础上，我们将系统地研究数据如何使我们的局部宇宙环境结构化，如果允许迄今为止被忽视的耦合，在这种模型中线性结构的形成如何进行，引力光偏转如何约束LTB模型，如何解释宇宙微波背景中的温度波动以及非线性结构的形成如何进行。研究结果有望大大收紧对LTB模型的理论和实证约束。

Is it possible that the apparently accelerated expansion of the Universe is not due to the repulsive effect of dark energy, but mimicked by the behaviour of a huge, underdense local environment? This question has often been addressed. A particularly suitable if idealised framework is provided by the class of Lemaître-Tolman-Bondi (LTB) solutions of General Relativity. Results achieved so far in this context seem to indicate that recent cosmological data rule out the hypothesis that we may be living in an inhomogeneous universe under certain restrictive assumptions, but are not in conflict with an LTB interpretation under more liberal conditions. We propose to extend existing studies in a five-fold way. We shall select those models from the LTB class that have a synchronous Big Bang. On this foundation, we shall then study systematically how the data allow our local cosmic environment to be structured, how linear structure formation proceeds in such models if couplings are allowed that have so far been neglected, how gravitational light deflection constrains LTB models, how temperature fluctuations in the cosmic microwave background must be interpreted and how non-linear structure formation proceeds. The results are expected to tighten the theoretical and empirical constraints on LTB models substantially.