Lagrangian theory of structure formation in pressure-supported cosmological fluids
Lagrangian theory of structure formation in pressure-supported cosmological fluids
复制标题
压力支撑宇宙流体结构形成的拉格朗日理论
DOI：
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发表时间：
1998
影响因子：
6.5
通讯作者：
T. Buchert
中科院分区：
文献类型：
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作者：
S. Adler;T. Buchert
宇宙流体中结构形成的拉格朗日理论，仅限于物质模型“尘埃”，提供了层流状态下宇宙中大尺度结构的成功模型，即，其中流体流是单流的并且“灰尘”壳是光滑的。在壳层穿越时期之后，预期会有质的不同行为，因为一般来说，由多流力驱动的各向异性应力出现在无碰撞物质中。在本文中，我们提供了基本框架的压力支持的流体建模，限制注意力各向同性应力和压力的情况下，可以作为密度的函数。我们推导了拉格朗日演化方程的控制集，并利用拉格朗日微扰理论研究了所得到的系统。我们讨论了一阶方程，并将其与欧拉引力不稳定性理论以及平面对称坍缩的情况进行了比较。我们得到一个构造规则，允许从已知的欧拉理论的一阶解导出拉格朗日理论的一阶解，从而将Zel'dovich的外插思想扩展到多流区。这些解决方案可以用来概括目前的结构形成模型的“粘附近似”的精神。
The Lagrangian theory of structure formation in cos- mological fluids, restricted to the matter model "dust", provides successful models of large-scale structure in the Universe in the laminar regime, i.e., where the fluid flow is single-streamed and "dust"-shells are smooth. Beyond the epoch of shell-crossing a qualitatively different behavior is expected, since in general anisotropic stresses powered by multi-stream forces arise in col- lisionless matter. In this paper we provide the basic framework for the modeling of pressure-supported fluids, restricting atten- tion to isotropic stresses and to the cases where pressure can be given as a function of the density. We derive the governing set of Lagrangian evolution equations and study the resulting system using Lagrangian perturbation theory. We discuss the first-order equations and compare them to the Eulerian theory of gravita- tional instability, as well as to the case of plane-symmetric col- lapse. We obtain a construction rule that allows to derive first- order solutions of the Lagrangian theory from known first-order solutions of the Eulerian theory and so extend Zel'dovich's ex- trapolation idea into the multi-streamed regime. These solutions can be used to generalize current structure formation models in the spirit of the "adhesion approximation".