Arithmetic with X-ray images of galaxy clusters: effective equation of state for small-scale perturbations in the ICM
Arithmetic with X-ray images of galaxy clusters: effective equation of state for small-scale perturbations in the ICM
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DOI：
10.1093/mnras/stw2044
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发表时间：
2016-11-21
影响因子：
4.8
通讯作者：
Zhuravleva, I.
中科院分区：
文献类型：
--
作者：
Churazov, E.;Arevalo, P.;Zhuravleva, I.
我们讨论了一种新的技术，操纵星系团的X射线图像，以揭示小尺度的密度/温度扰动的性质在团内介质（ICM）。正如我们所示，这种技术可以用来区分声波和等压扰动钱德拉英仙座和M87/室女座星系团的图像。操纵的图像与无线电数据和详细的频谱分析结果的比较表明，这种方法成功地分类的扰动类型，并有助于揭示其性质。对于M87和英仙座星系团的中心区域（5-100 kpc），这种分析表明，观测到的图像主要是由等压扰动，其次是由相对论等离子体气泡和弱激波引起的扰动。这样的层次结构最好的解释是在一个“缓慢”的活动星系核反馈的情况下，当一个中央黑洞的机械能输出的大部分被捕获的气泡焓，逐渐释放在浮力上升的气泡。“图像算法”最适用于突出的结构和具有良好统计的数据集，可视化给定有效状态方程的扰动。同样的方法可以通过对不同能带的X射线图像中的表面亮度波动进行交叉谱分析来扩展到微弱的扰动。
We discuss a novel technique of manipulating X-ray images of galaxy clusters to reveal the nature of small-scale density/temperature perturbations in the intracluster medium (ICM). As we show, this technique can be used to differentiate between sound waves and isobaric perturbations in Chandra images of the Perseus and M87/Virgo clusters. The comparison of the manipulated images with the radio data and with the results of detailed spectral analysis shows that this approach successfully classifies the types of perturbations and helps to reveal their nature. For the central regions (5-100 kpc) of the M87 and Perseus clusters, this analysis suggests that observed images are dominated by isobaric perturbations, followed by perturbations caused by bubbles of relativistic plasma and weak shocks. Such a hierarchy is best explained in a 'slow' active galactic nuclei feedback scenario, when much of the mechanical energy output of a central black hole is captured by the bubble enthalpy that is gradually released during buoyant rise of the bubbles. The 'image arithmetic' works best for prominent structure and for data sets with excellent statistics, visualizing the perturbations with a given effective equation of state. The same approach can be extended to faint perturbations via cross-spectrum analysis of surface brightness fluctuations in X-ray images in different energy bands.