Testing the accuracy of halo occupation distribution modelling using hydrodynamic simulations
Testing the accuracy of halo occupation distribution modelling using hydrodynamic simulations
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DOI：
10.1093/mnras/stz3442
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发表时间：
2019-08
影响因子：
4.8
通讯作者：
G. Beltz-Mohrmann;A. Berlind;A. O. Szewciw
中科院分区：
文献类型：
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作者：
G. Beltz-Mohrmann;A. Berlind;A. O. Szewciw
晕模型提供了一种简单且计算成本低廉的方法来研究星系与其暗物质晕之间的联系。然而，这些模型依赖于这样的假设：重子的作用可以在建模过程中轻松参数化。我们的目的是检查晕占据分布 (HOD) 模型重现在两种不同的流体动力学模拟（Illustris 和 EAGLE）中发现的星系聚类的能力。对于每次模拟，我们都会在两个不同的光度阈值样本上测量几个星系聚类统计数据。然后，我们将一个简单的五参数 HOD（分别适合每个模拟）应用于相应的仅暗物质模拟，并测量相同的聚类统计数据。我们发现，在流体动力学模拟中，晕质量函数转移到较低质量，导致当 HOD 应用于仅暗物质模拟时，星系数密度过高。然而，重子改变质量函数的确切方式在两个模拟中明显不同。在每次模拟中对晕质量函数进行校正后，HOD 能够准确地再现高光度星系样本的所有聚类统计数据。对于低光度样本，我们发现证据表明，除了校正晕质量函数之外，HOD 中的空间、速度和组装偏差参数对于准确再现聚类统计数据也是必要的。
Halo models provide a simple and computationally inexpensive way to investigate the connection between galaxies and their dark matter haloes. However, these models rely on the assumption that the role of baryons can easily be parametrized in the modelling procedure. We aim to examine the ability of halo occupation distribution (HOD) modelling to reproduce the galaxy clustering found in two different hydrodynamic simulations, Illustris and EAGLE. For each simulation, we measure several galaxy clustering statistics on two different luminosity threshold samples. We then apply a simple five parameter HOD, which was fit to each simulation separately, to the corresponding dark matter-only simulations, and measure the same clustering statistics. We find that the halo mass function is shifted to lower masses in the hydrodynamic simulations, resulting in a galaxy number density that is too high when an HOD is applied to the dark matter-only simulation. However, the exact way in which baryons alter the mass function is remarkably different in the two simulations. After applying a correction to the halo mass function in each simulation, the HOD is able to accurately reproduce all clustering statistics for the high luminosity sample of galaxies. For the low luminosity sample, we find evidence that in addition to correcting the halo mass function, including spatial, velocity, and assembly bias parameters in the HOD is necessary to accurately reproduce clustering statistics.