A Simulation of the Intracluster Medium With Feedback from Cluster Galaxies
A Simulation of the Intracluster Medium With Feedback from Cluster Galaxies
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星团内介质的反馈模拟
DOI：
10.1086/175022
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发表时间：
1993
期刊：
影响因子：
--
通讯作者：
A. Evrard
中科院分区：
文献类型：
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作者：
C. A. Metzler;A. Evrard
我们详细介绍了方法和报告的第一个结果，来自一个昏迷大小的星系团的形成和演化的三维流体动力学和n体模拟，目的是研究热的，x射线发射的星系团内介质的历史。星系团气体、星系和暗物质都包含在这个模型中。星系和暗物质受到引力的影响；团簇气体还会受到激波加热和PdV功等流体动力学效应的影响。这是第一次在三维空间中，我们加入了模拟星系中由风喷出的加工气体的模型，包括加热和重元素富集。为了比较，我们采用了一个“纯落”模拟，使用相同的初始条件，但没有星系或风。为了确定可能模型的边界，我们采用了星系反馈的极端喷射历史。正如预期的那样，反馈提高了星系团内气体的熵，防止它坍缩到像落入模型那样高的密度。这种效应在高红移形成的亚星团中更为明显。有反馈的星团的x射线亮度总是较低，但光度演化速度比纯落入星团快。即使采用极端喷射模型，最终气体温度也只比落入模型高15%左右。径向温度分布在1.5 Mpc范围内非常接近等温。反馈模型中的星系团的速度色散比暗物质低约15%。这导致星系与气体的比能量之比小于1，β（亚规格）约为0.7。跌落模型预测beta（子规范）约为1.2。随着时间的推移，随着星团复杂的动态历史，这些值会发生较大的偏移。反馈对x射线发射的形貌影响很小。这两个星系团的发射分布都可以用标准的β模型很好地描述，β（亚拟合）大约等于0.7 - 0.9。基于流体静力平衡假设和β模型适用性的x射线质量估计在这两种情况下都是相当准确的。一个强烈的径向铁丰度梯度是存在的，这是随着时间的推移星系密度曲线变陡的结果。使用宽视场（约45分钟）的非成像探测器进行光谱观测会显著地涂抹梯度。ASCA卫星提供的弧分分辨率观测可以很容易地分辨出梯度。
We detail method and report first results from a three-dimensional hydrodynamical and N-body simulation of the formation and evolution of a Coma-sized cluster of galaxies, with the intent of studying the history of the hot, X-ray emitting intracluster medium. Cluster gas, galaxies, and dark matter are included in the model. The galaxies and dark matter fell gravitational forces; the cluster gas also undergoes hydrodynamical effects such as shock heating and PdV work. For the first time in three dimensions, we include modeling of ejection of processed gas from the simulated galaxies by winds, including heating and heavy element enrichment. For comparison, we employ a `pure infall' simulation using the same initial conditions but with no galaxies or winds. We employ an extreme ejection history for galactic feedback in order to define the boundary of likely models. As expected, feedback raises the entropy of the intracluster gas, preventing it from collapsing to densities as high as those attained in the infall model. The effect is more pronounced in subclusters formed at high redshift. The cluster with feedback is always less X-ray luminous, but experiences more rapid luminosity evolution, than the pure infall cluster. Even employing an extreme ejection model, the final gas temperature is only approximately 15% larger than in the infall model. The radial temperature profile is very nearly isothermal within 1.5 Mpc. The cluster galaxies in the feedback model have a velocity dispersion approximately 15% lower than the dark matter. This results in the true ratio of specific energies in galaxies to gas being less than one, beta(sub spec) approximately 0.7. The infall model predicts beta(sub spec) approximately 1.2. Large excursions in these values occur over time, following the complex dynamical history of the cluster. The morphology of the X-ray emission is little affected by feedback. The emission profiles of both clusters are well described by the standard beta-model with beta(sub fit) approximately equal to 0.7 - 0.9. X-ray mass estimates based on the assumptions of hydrostatic equilibrium and the applicability of the beta-model are quite accurate in both cases. A strong, radial iron abundance gradient is present, which develops as a consequence of the steepening of the galaxy density profile over time. Spectroscopic observations using nonimaging detectors with wide (approximately 45 min) fields of view dramatically smear the gradient. Observations with arcminute resolution, made available with the ASCA satellite, would readily resolve the gradient.