Evolution of linear perturbations in spherically symmetric dust spacetimes
Evolution of linear perturbations in spherically symmetric dust spacetimes
复制标题
球对称尘埃时空中线性扰动的演化
DOI：
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发表时间：
2013
期刊：
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通讯作者：
D. Pollney
中科院分区：
文献类型：
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作者：
S. February;J. Larena;C. Clarkson;D. Pollney
我们提出了采用新方法求解主方程的数值代码的结果，该主方程描述了球对称但非均匀背景中线性扰动的演化。该方法可用于模拟多种物理结构，例如结构形成的相对论校正、引力波 (GW) 的透镜效应以及宇宙空洞模型中扰动的演化。本文重点讨论后一个问题，即线性区域哈勃尺度空洞中的结构形成。这比均匀和各向同性背景的线性扰动要复杂得多，因为非均匀背景导致密度扰动和时空几何的旋转模式以及引力波之间的耦合。之前对该问题的分析忽略了这种耦合，希望这种近似不会影响此类模型中结构形成的整体动力学。我们表明，对于千兆秒差距的空洞，密度对比的演化可以很好地近似于先前研究的仅针对超大规模模式的解耦演化。然而，虚空内引力势的演化在10%以上的水平上是不准确的，在小尺度上更糟。
We present results from a numerical code implementing a new method to solve the master equations describing the evolution of linear perturbations in a spherically symmetric but inhomogeneous background. This method can be used to simulate several configurations of physical interest, such as relativistic corrections to structure formation, the lensing of gravitational waves (GWs) and the evolution of perturbations in a cosmological void model. This paper focuses on the latter problem, i.e. structure formation in a Hubble scale void in the linear regime. This is considerably more complicated than linear perturbations of a homogeneous and isotropic background because the inhomogeneous background leads to coupling between density perturbations and rotational modes of the spacetime geometry, as well as GWs. Previous analyses of this problem ignored this coupling in the hope that the approximation does not affect the overall dynamics of structure formation in such models. We show that for a giga-parsec void, the evolution of the density contrast is well approximated by the previously studied decoupled evolution only for very large-scale modes. However, the evolution of the gravitational potentials within the void is inaccurate at more than the 10% level, and is even worse on small scales.