The inner structure of ΛCDM haloes – III. Universality and asymptotic slopes
The inner structure of ΛCDM haloes – III. Universality and asymptotic slopes
复制标题
DOI：
10.1111/j.1365-2966.2004.07586.x
复制
发表时间：
2003-11
影响因子：
4.8
通讯作者：
J. Navarro;E. Hayashi;C. Power;A. Jenkins;C. Frenk;S. White;V. Springel;J. Stadel;T. Q. U. O. Vict
中科院分区：
文献类型：
--
作者：
J. Navarro;E. Hayashi;C. Power;A. Jenkins;C. Frenk;S. White;V. Springel;J. Stadel;T. Q. U. O. Vict
我们调查了冷暗物质（ACDM）晕的质量分布，使用一套数值模拟跨越五十年的晕质量，从矮星系到丰富的星系团。这些晕通常在维里半径（r 200）内有几百万个粒子，允许在半径小于r 200的1%的情况下进行可靠的质量分布估计。我们的分析证实了Navarro，Frenk和白色（NFW）的建议，ACDM晕质量分布的形状与幂律有很大的不同，对质量的依赖很小。球形平均密度分布的对数斜率，如β = -d In p/d In r所测量的，朝向中心单调减小，并且在特征半径r-2内变得比等温（β < 2）更浅。NFW提出的拟合公式提供了一个相当好的近似的密度和圆速度分布的个人晕;圆速度通常偏离NFW最佳拟合的径向范围内，数值解析<10%。或者，从NFW最佳拟合的系统偏差也是明显的。在r-2内，模拟晕的轮廓随着半径逐渐变浅，其结果是，NFW拟合倾向于低估这些区域的暗物质密度。这种差异被解释为表明具有渐近内斜率β 0 <$β（r = 0）<$1.5的急剧发散的尖点。我们的研究结果提出了不同的解释。我们使用密度和最内层解析半径处的封闭质量来对β 0施加强约束：密度尖点如r-1.5那样陡峭与我们的大多数模拟不一致，尽管β 0 = 1仍然与我们的数据一致。我们的密度分布没有显示出收敛到一个定义良好的渐近内幂律的迹象。我们提出了一个简单的公式，再现的径向依赖的斜率比NFW的配置文件，因此可以尽量减少错误时，我们的结果向内外推到半径还没有可靠的数值模拟探测。
We investigate the mass profile of cold dark matter (ACDM) haloes using a suite of numerical simulations spanning five decades in halo mass, from dwarf galaxies to rich galaxy clusters. These haloes typically have a few million particles within the virial radius (r 200 ), allowing robust mass profile estimates down to radii <1 per cent of r 200 . Our analysis confirms the proposal of Navarro, Frenk & White (NFW) that the shape of the ACDM halo mass profiles differs strongly from a power law and depends little on mass. The logarithmic slope of the spherically averaged density profile, as measured by β = -d In p/d In r, decreases monotonically towards the centre and becomes shallower than isothermal (β < 2) inside a characteristic radius, r -2 . The fitting formula proposed by NFW provides a reasonably good approximation to the density and circular velocity profiles of individual haloes; circular velocities typically deviate from NFW best fits by <10 per cent over the radial range that is numerically well resolved. Alternatively, systematic deviations from the NFW best fits are also noticeable. Inside r -2 , the profile of simulated haloes becomes shallower with radius more gradually than predicted and, as a result, NFW fits tend to underestimate the dark matter density in these regions. This discrepancy has been interpreted as indicating a steeply divergent cusp with asymptotic inner slope, β 0 ≡ β(r = 0) ∼ 1.5. Our results suggest a different interpretation. We use the density and enclosed mass at our innermost resolved radii to place strong constraints on β 0 : density cusps as steep as r -1.5 are inconsistent with most of our simulations, although β 0 = 1 is still consistent with our data. Our density profiles show no sign of converging to a well-defined asymptotic inner power law. We propose a simple formula that reproduces the radial dependence of the slope better than the NFW profile, and so may minimize errors when extrapolating our results inward to radii not yet reliably probed by numerical simulations.