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arXiv 1407.5729astro-ph.GAastro-ph.CO
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ICM中的金属分布--十二个星系团的综合数值研究

Metal distribution in the ICM - a comprehensive numerical study of twelve galaxy clusters

Harald Höller, Josef Stöckl, Andrew Benson, Markus Haider, Dominik Steinhauser, Lorenzo Lovisari, Florian Pranger

摘要:

我们提出了一个模拟装置,用于研究团内介质(ICM)的动力学和化学演化,并分析了12个星系团的样本,这些星系团在动力学(合并前,合并,维里化)和总质量(M vir = 1.17 x 10^14 - 1.06 x 10^15 M)上都是不同的。我们分析了ICM中金属质量分数与红移的函数关系,并讨论了径向趋势以及投影的2D金属丰度图。该装置结合了高质量分辨率的N体模拟与半解析的星系形成模型Galacticus的亚网格物理(如星系风和冲压压力剥离)在宇宙流体动力学模拟一致的治疗。讨论了Galacticus和ICM的FLASH水模拟之间的接口,相对于恒星形成率的历史,径向恒星形成的趋势,在星系团,在不同的红移和金属丰度的观测。作为对风模型鲁棒性的测试,我们比较了三种不同方法的处方。对于直接从银河系的风模型,我们发现平均ICM金属丰度在0.2 - 0.8Z之间的内部1 Mpc在z = 0。对金属质量分数的主要贡献来自星系风。流出的有效地混合在ICM,导致稳定的均匀化的金属,直到冲压压力剥离成为有效的低红移。我们发现在冷核心的内部~ 200 kpc内,金属质量分数有一个非常特殊但又很常见的下降,这是由于我们的模型中外部压力对风的抑制以及这些密集区域形成后缺乏混合的综合作用。

英文摘要:

We present a simulation setup for studying the dynamical and chemical evolution of the intracluster medium (ICM) and analyze a sample of 12 galaxy clusters that are diverse both kinetically (pre-merger, merging, virialized) and in total mass (M vir = 1.17 x 10^14 - 1.06 x 10^15 M). We analyzed the metal mass fraction in the ICM as a function of redshift and discuss radial trends as well as projected 2D metallicity maps. The setup combines high mass resolution N-body simulations with the semi-analytical galaxy formation model Galacticus for consistent treatment of the subgrid physics (such as galactic winds and ram-pressure stripping) in the cosmological hydrodynamical simulations. The interface between Galacticus and the hydro simulation of the ICM with FLASH is discussed with respect to observations of star formation rate histories, radial star formation trends in galaxy clusters, and the metallicity at different redshifts. As a test for the robustness of the wind model, we compare three prescriptions from different approaches. For the wind model directly taken from Galacticus, we find mean ICM metallicities between 0.2 - 0.8Z within the inner 1Mpc at z = 0. The main contribution to the metal mass fraction comes from galactic winds. The outflows are efficiently mixed in the ICM, leading to a steady homogenization of metallicities until ram-pressure stripping becomes effective at low redshifts. We find a very peculiar and yet common drop in metal mass fractions within the inner ~200kpc of the cool cores, which is due to a combination of wind suppression by outer pressure within our model and a lack of mixing after the formation of these dense regions.

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