Evolution of Buoyant Bubbles in M87
Evolution of Buoyant Bubbles in M87
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DOI：
10.1086/321357
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发表时间：
2000-08
期刊：
影响因子：
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通讯作者：
E. Churazov;M. Brüggen;C. Kaiser;H. Böhringer;W. Forman
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文献类型：
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作者：
E. Churazov;M. Brüggen;C. Kaiser;H. Böhringer;W. Forman
在星系M87周围的中央~50 kpc区域，X射线和无线电发射特征的形态强烈表明，宇宙射线的浮力气泡（由星系早期的核活跃阶段膨胀）以大约一半的声速通过冷却气体上升。在没有强表面张力的情况下，最初的球形气泡在通过外部介质上升时将转变为环面。这样的结构可以在M87晕的射电图像中找到。在上升过程中，气泡会将相对较冷的X射线发射气体从冷却流的中心区域提升到更远的距离。这种气体比环境气体更冷，并且具有更高的体积发射率。因此，上升的“无线电”气泡可能会被拉长的X射线特征所跟踪，就像在M87中观察到的那样。我们进行了简单的流体动力学模拟，定性地说明在M87环境中的浮力气泡的演变。
The morphology of the X-ray- and radio-emitting features in the central ~50 kpc region around the galaxy M87 strongly suggests that buoyant bubbles of cosmic rays (inflated by an earlier nuclear active phase of the galaxy) rise through the cooling gas at roughly half the sound speed. In the absence of strong surface tension, initially spherical bubbles will transform into tori as they rise through an external medium. Such structures can be identified in the radio images of the halo of M87. During their rise, bubbles will uplift relatively cool X-ray-emitting gas from the central regions of the cooling flow to larger distances. This gas is colder than the ambient gas and has a higher volume emissivity. As a result, rising "radio" bubbles may be trailed by elongated X-ray features, as indeed is observed in M87. We performed simple hydrodynamic simulations to illustrate qualitatively the evolution of buoyant bubbles in the M87 environment.