标题： 带有壳层交叉的球形坍缩模型 显示英文标题

标题： The spherical collapse model with shell crossing

摘要： 在本工作中，我们通过球对称坍缩模型结合壳层交叉效应来研究暗物质晕的形成和演化。 我们提出一个框架，通过时间上对包含相同质量分数的单个物质壳进行数值跟踪，从而正确处理这种效应。 在这一初步步骤中，我们不考虑角动量、速度弥散或三轴性。 在此框架——称为球壳追踪器（SST）中，我们研究了晕的演化与驻留质量、所采用的壳层质量分数以及不同宇宙学参数之间的依赖关系。 我们发现，我们的结果对所考虑的晕驻留质量或壳层质量分数的变化非常敏感。 然而，我们得到的结果对宇宙学的依赖可以忽略不计。 此外，我们表明壳层交叉效应在晕达到半径稳定和驻留平衡的方式中起着关键作用。 我们发现，文献中当前采用的驻留时刻的实际密度对比度delta_vir可能不够准确。 在此背景下，我们强调了与定义晕的驻留质量和驻留半径相关的问题。 这里找到的结果是否可以通过用解析近似跟踪壳层仍需进一步探索。 显示英文摘要

摘要： In this work, we study the formation and evolution of dark matter halos by means of the spherical infall model with shell-crossing. We present a framework to tackle this effect properly based on the numerical follow-up, with time, of that individual shell of matter that contains always the same fraction of mass with respect to the total mass. In this first step, we do not include angular momentum, velocity dispersion or triaxiality. Within this framework - named as the Spherical Shell Tracker (SST) - we investigate the dependence of the evolution of the halo with virial mass, with the adopted mass fraction of the shell, and for different cosmologies. We find that our results are very sensitive to a variation of the halo virial mass or the mass fraction of the shell that we consider. However, we obtain a negligible dependence on cosmology. Furthermore, we show that the effect of shell-crossing plays a crucial role in the way that the halo reaches the stabilization in radius and the virial equilibrium. We find that the values currently adopted in the literature for the actual density contrast at the moment of virialization, delta_vir, may not be accurate enough. In this context, we stress the problems related to the definition of a virial mass and a virial radius for the halo. The question of whether the results found here may be obtained by tracking the shells with an analytic approximation remains to be explored.