A non-ideal magnetohydrodynamic GADGET: simulating massive galaxy clusters
A non-ideal magnetohydrodynamic GADGET: simulating massive galaxy clusters
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DOI：
10.1111/j.1365-2966.2011.19523.x
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发表时间：
2011-07
影响因子：
4.8
通讯作者：
A. Bonafede;K. Dolag;F. Stasyszyn;G. Murante;S. Borgani
中科院分区：
文献类型：
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作者：
A. Bonafede;K. Dolag;F. Stasyszyn;G. Murante;S. Borgani
星系团团内介质（ICM）的磁场在过去已经通过不同的方法进行了研究。到目前为止，我们对这些磁场的起源，以及它们在结构形成过程中的作用以及它们与ICM其他成分的相互作用的理解仍然有限。在未来几年，新一代的射电望远镜将提供新的数据，这些数据将有可能对星系团中的磁场特性进行限制。在这里，我们展示了一组大质量星系团（Mv ≥ 1015 h−1 M <$）的放大模拟。这是详细研究结构形成过程中磁场演化的理想样品。ICM内气体的湍流运动将以宏观磁阻率ηm的形式表现出来，必须明确考虑到这一点，特别是在分辨率极限以下的尺度上。我们已经调整了Dolag & Stasyszyn的磁流体动力学（MHD）小工具代码，以包括对磁阻率的处理，并且我们第一次包括了非理想MHD方程，以更好地跟踪星系团内磁场的演化。我们研究磁电阻率ηm的值需要匹配的磁场轮廓来自无线电观测。我们发现，要恢复从后发座星系团射电观测中推断出的磁场轮廓的形状，需要ηm = 6 × 1027 cm 2 s−1。在我们的分辨率极限下，该值与ICM内湍流运动的预期水平一致。模拟团簇的磁场分布可以用类β模型的磁场分布拟合，参数的离散度很小。我们还发现，团簇的温度、密度和熵分布依赖于磁电阻率常数，当磁电阻率增大时，团簇内部区域的温度、密度和熵分布更加平坦。
Magnetic fields in the intra-cluster medium (ICM) of galaxy clusters have been studied in the past through different methods. So far, our understanding of the origin of these magnetic fields, as well as their role in the process of structure formation and their interplay with the other constituents of the ICM, is still limited. In the coming years, the up-coming generation of radio telescopes is going to provide new data that will have the potential of setting constraints on the properties of magnetic fields in galaxy clusters. Here, we present zoomed-in simulations for a set of massive galaxy clusters (Mv ≥ 1015 h−1 M⊙). This is an ideal sample to study the evolution of the magnetic field during the process of structure formation in detail. Turbulent motions of the gas within the ICM will manifest themselves in a macroscopic magnetic resistivity ηm, which has to be taken explicitly into account, especially at scales below the resolution limit. We have adapted the magnetohydrodynamic (MHD) gadget code by Dolag & Stasyszyn to include the treatment of the magnetic resistivity, and for the first time we have included non-ideal MHD equations to better follow the evolution of the magnetic field within the galaxy clusters. We investigate which value of the magnetic resistivity ηm is required to match the magnetic field profile derived from radio observations. We find that a value of ηm∼ 6 × 1027 cm2 s−1 is necessary to recover the shape of the magnetic field profile inferred from radio observations of the Coma cluster. This value agrees well with the expected level of turbulent motions within the ICM at our resolution limit. The magnetic field profiles of the simulated clusters can be fitted by a β-model-like profile, with small dispersion of the parameters. We also find that the temperature, density and entropy profiles of the clusters depend on the magnetic resistivity constant, having flatter profiles in the inner regions when the magnetic resistivity increases.