一种改进的非线性密度演化的半解析球塌缩模型
An Improved Semi-Analytical Spherical Collapse Model for Non-linear Density Evolution
摘要：
我们推导出一个半解析扩展的结构形成的球形塌陷模型，考虑到偏离球对称和壳交叉的影响，这是重要的非线性制度。我们的模型的设计，使它预测的奇特的速度和密度对比度，同意在该地区的N体模拟的结果，这样的比较可以合理地作出之间的关系。在转向之前，当未修改的球形塌陷模型被认为是一个很好的近似时，两个模型的预测几乎完全一致。晚时间占主导地位的暗能量分量的影响也被考虑在内。改进的球形坍缩模型是一个有用的工具，当一个人需要一个很好的近似不仅是密度对比度的演变，但它的轨迹。此外，分析拟合公式是足够简单的地方，可以使用标准的球形崩溃，但它的优点是，它包括一个现实的模型的影响维里化。
英文摘要：
We derive a semi-analytical extension of the spherical collapse model of structure formation that takes account of the effects of deviations from spherical symmetry and shell crossing which are important in the non-linear regime. Our model is designed so that it predicts a relation between the peculiar velocity and density contrast that agrees with the results of N-body simulations in the region where such a comparison can sensibly be made. Prior to turnaround, when the unmodified spherical collapse model is expect to be a good approximation, the predictions of the two models coincide almost exactly. The effects of a late time dominating dark energy component are also taken into account. The improved spherical collapse model is a useful tool when one requires a good approximation not just to the evolution of the density contrast but also its trajectory. Moreover, the analytical fitting formulae presented is simple enough to be used anywhere where the standard spherical collapse might be used but with the advantage that it includes a realistic model of the effects of virialisation.
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