标题： 微波背景各向异性与非线性结构 I. 改进的理论模型 显示英文标题

标题： Microwave Background Anisotropies and Nonlinear Structures I. Improved Theoretical Models

摘要： 提出了一种建模宇宙球对称非均匀性的新方法。这些非均匀性具有有限大小且是补偿的，因此它们在其边界之外不会产生任何可测量的引力作用。扰动外部区域由一个弗里德曼-罗伯逊-沃克（FRW）宇宙表示，我们用它来研究由星系团诱导的宇宙微波背景（CMB）各向异性。所有计算都在单一的全局坐标系中完成，并完全包含了非线性引力效应。这里采用的规范选择的一个优点是，所得方程本质上是牛顿形式的。检查指定初始数据的问题表明，这里提出的新型具有许多优于“瑞士奶酪”和其他模型的优势。这里导出的方程的数值实现将在后续论文中描述。 显示英文摘要

摘要： A new method is proposed for modelling spherically symmetric inhomogeneities in the Universe. The inhomogeneities have finite size and are compensated, so they do not exert any measurable gravitational force beyond their boundary. The region exterior to the perturbation is represented by a Friedmann-Robertson-Walker (FRW) Universe, which we use to study the anisotropy in the cosmic microwave background (CMB) induced by the cluster. All calculations are performed in a single, global coordinate system, with nonlinear gravitational effects fully incorporated. An advantage of the gauge choices employed here is that the resultant equations are essentially Newtonian in form. Examination of the problem of specifying initial data shows that the new model presented here has many advantages over `Swiss cheese' and other models. Numerical implementation of the equations derived here is described in a subsequent paper.