The diversity and similarity of simulated cold dark matter haloes
The diversity and similarity of simulated cold dark matter haloes
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DOI：
10.1111/j.1365-2966.2009.15878.x
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发表时间：
2008-10
影响因子：
4.8
通讯作者：
J. Navarro;A. Ludlow;V. Springel;Jie-Shuang Wang;M. Vogelsberger;S. White;A. Jenkins;C. Frenk;A. Helmi
中科院分区：
文献类型：
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作者：
J. Navarro;A. Ludlow;V. Springel;Jie-Shuang Wang;M. Vogelsberger;S. White;A. Jenkins;C. Frenk;A. Helmi
我们研究的质量，速度色散和各向异性配置文件的λ冷暗物质（λ CDM）晕使用一套N体模拟前所未有的数值分辨率。宝瓶座项目遵循六个不同的星系大小的晕模拟多次在不同的数值分辨率，允许数值收敛直接评估的形成。最高分辨率的模拟使用44亿个粒子代表单个暗物质晕，其中11亿个粒子最终位于维里半径内。我们的分析证实了一些结果声称早期的工作，并澄清了一些问题，在最近的文献中可能会发现相互冲突的索赔。Lambda CDM晕的质量分布与Navarro、Frenk和白色提出的形式略有系统性的偏离。球形平均密度轮廓向内逐渐变浅，并且在最内部的分辨半径处，对数斜率为γ，相当于-d ln/d ln r小于或接近1。最近声称的与r-1.2成比例的渐近内斜率一样陡，显然被排除了。伽马的径向依赖性很好地近似于幂律，伽马与r α成比例（Einasto剖面）。的形状参数，α，略有不同，但显着从晕晕，这意味着的质量配置文件的λ CDM晕不是严格的通用：不同的晕不能，在一般情况下，重新缩放看起来相同。相似性的结果也可以在速度弥散分布中看到，并与密度分布中的结果相关，以便保持球形平均伪相空间密度的幂律形式，/Sigma 3与r-1.875成比例。这里的指数与Bertschinger的相似性解相同，该解用于从均匀的爱因斯坦-德西特宇宙中自相似地落向一个点质量。这种惊人行为的起源尚不清楚，但其稳健性表明，它反映了Lambda CDM晕的基本结构特性。我们的结论是可靠的，半径低于0.4%的维里半径，提供了定义良好的预测晕结构时，重子效应被忽略，因此，一个指导性的理论模板，对诱导的修改的重子组件的真实的星系可以判断。
We study the mass, velocity dispersion and anisotropy profiles of Lambda cold dark matter (Lambda CDM) haloes using a suite of N-body simulations of unprecedented numerical resolution. The Aquarius Project follows the formation of six different galaxy-sized haloes simulated several times at varying numerical resolution, allowing numerical convergence to be assessed directly. The highest resolution simulation represents a single dark matter halo using 4.4 billion particles, of which 1.1 billion end up within the virial radius. Our analysis confirms a number of results claimed by earlier work, and clarifies a few issues where conflicting claims may be found in the recent literature. The mass profile of Lambda CDM haloes deviates slightly but systematically from the form proposed by Navarro, Frenk & White. The spherically averaged density profile becomes progressively shallower inwards and, at the innermost resolved radius, the logarithmic slope is gamma equivalent to - d ln /d ln r less than or similar to 1. Asymptotic inner slopes as steep as the recently claimed proportional to r-1.2 are clearly ruled out. The radial dependence of gamma is well approximated by a power law, gamma proportional to r alpha (the Einasto profile). The shape parameter, alpha, varies slightly but significantly from halo to halo, implying that the mass profiles of Lambda CDM haloes are not strictly universal: different haloes cannot, in general, be rescaled to look identical. Departures from similarity are also seen in velocity dispersion profiles and correlate with those in density profiles so as to preserve a power-law form for the spherically averaged pseudo-phase-space density, /Sigma 3 proportional to r-1.875. The index here is identical to that of Bertschinger's similarity solution for self-similar infall on to a point mass from an otherwise uniform Einstein-de Sitter universe. The origin of this striking behaviour is unclear, but its robustness suggests that it reflects a fundamental structural property of Lambda CDM haloes. Our conclusions are reliable down to radii below 0.4 per cent of the virial radius, providing well-defined predictions for halo structure when baryonic effects are neglected, and thus an instructive theoretical template against which the modifications induced by the baryonic components of real galaxies can be judged.