暗物质晕破缺幂律和双幂律模型的动力学结构
The dynamical structure of broken power-law and double power-law models for dark matter haloes
摘要：
星系运动学和引力透镜效应是限制星系尺度上暗物质分布的两种互补方式。在动力学研究中采用的典型暗物质密度剖面不能轻易地用于透镜效应研究。理想情况下，应该使用一个质量模型，它具有现实的暗物质分布的全局特性，并且允许分析计算放大率和偏转角。一个简单的模型与这些属性，破幂律（BPL）模型，最近被引入。我们研究的动力学结构的家庭的BPL模型。我们推导了基本动力学性质的简单封闭表达式，并在速度各向同性的假设下研究了分布函数。我们发现，没有一个具有现实参数的BPL模型具有各向同性的分布函数，在整个相空间是积极的，这意味着BPL模型不能支持各向同性的速度分布，或模型具有更径向各向异性的轨道结构。这一结果在一定程度上限制了BPL家族作为透镜研究工具的吸引力。更一般地说，我们发现，并不是所有的成员的一般家庭的双幂律或赵模型，通常用于模拟暗物质晕，可以支持一个各向同性或径向各向异性的分布函数。换句话说，即使对于具有良好密度分布的球对称模型，分布函数也可能变为负值。
英文摘要：
Galaxy kinematics and gravitational lensing are two complementary ways to constrain the distribution of dark matter on galaxy scales. The typical dark matter density profiles adopted in dynamical studies cannot easily be adopted in lensing studies. Ideally, a mass model should be used that has the global characteristics of realistic dark matter distributions, and that allows for an analytical calculation of the magnifications and deflection angles. A simple model with these properties, the broken-power-law (BPL) model, has very recently been introduced. We examine the dynamical structure of the family of BPL models. We derive simple closed expressions for basic dynamical properties, and study the distribution function under the assumption of velocity isotropy. We find that none of the BPL models with realistic parameters has an isotropic distribution function that is positive over the entire phase space, implying that the BPL models cannot be supported by an isotropic velocity distribution, or models with a more radially anisotropic orbital structure. This result limits the attractiveness of the BPL family as a tool for lensing studies to some degree. More generally, we find that not all members of the general family of double power-law or Zhao models, often used to model dark matter haloes, can be supported by an isotropic or radially anisotropic distribution function. In other words, the distribution function may become negative even for spherically symmetric models with a well-behaved density profile.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
