Evolution of the mass function of dark matter haloes
Evolution of the mass function of dark matter haloes
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DOI：
10.1046/j.1365-2966.2003.07113.x
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发表时间：
2003-12-01
影响因子：
4.8
通讯作者：
Governato, F
中科院分区：
文献类型：
--
作者：
Reed, D;Gardner, J;Governato, F
我们使用一个高分辨率的LambdaCDM数值模拟来计算暗物质晕的质量函数，在50h(-1)MPC体积中包含8000万个粒子，尺度上是矮小星系，红移为15。我们的低红移结果使我们能够探测远远超出先前宇宙学模拟范围的低西格玛密度涨落。Sheth&Torman质量函数与我们的所有数据都有很好的匹配，但红移10和更高的数据除外，其中它高估了晕数，随着红移的增加，高估了10(10)-10(11)M-的大约50%。我们的结果证实了以前的发现，即模拟的晕质量函数可以仅由质量分布的变化来描述，因此没有明显的红移依赖关系。我们为我们的数据提供了一个经验拟合，纠正了Sheth&Torman质量函数对极其罕见的天体的过度预测。这种过度预测对于使用类似稀有天体的数密度作为宇宙学探测器的研究具有重要意义。例如，高红移(z类似或等于6)类星体的数密度可能被高估了至少50%，这种类星体被认为是由涨落场中5西格玛峰值的光晕托管的。我们测试了我们的结果对力精度的敏感性，启动了红移和寻找晕轮算法。
We use a high-resolution LambdaCDM numerical simulation to calculate the mass function of dark matter haloes down to the scale of dwarf galaxies, back to a redshift of 15, in a 50 h(-1) Mpc volume containing 80 million particles. Our low-redshift results allow us to probe low-sigma density fluctuations significantly beyond the range of previous cosmological simulations. The Sheth & Tormen mass function provides an excellent match to all of our data except for redshifts of 10 and higher, where it overpredicts halo numbers increasingly with redshift, reaching roughly 50 per cent for the 10(10) -10(11) M-. haloes sampled at redshift 15. Our results confirm previous findings that the simulated halo mass function can be described solely by the variance of the mass distribution, and thus has no explicit redshift dependence. We provide an empirical fit to our data that corrects for the overprediction of extremely rare objects by the Sheth & Tormen mass function. This overprediction has implications for studies that use the number densities of similarly rare objects as cosmological probes. For example, the number density of high-redshift (z similar or equal to 6) QSOs, which are thought to be hosted by haloes at 5sigma peaks in the fluctuation field, are likely to be overpredicted by at least a factor of 50 per cent. We test the sensitivity of our results to force accuracy, starting redshift and halo-finding algorithm.