The quiescent intracluster medium in the core of the Perseus cluster
The quiescent intracluster medium in the core of the Perseus cluster
复制标题
DOI：
10.1038/nature18627
复制
发表时间：
2016-07
期刊：
影响因子：
64.8
通讯作者：
Hitomi Collaboration;F. Aharonian;H. Akamatsu;F. Akimoto;S. Allen;N. Anabuki;L. Angelini;K. Arnaud-K.-Arn
中科院分区：
文献类型：
--
作者：
Hitomi Collaboration;F. Aharonian;H. Akamatsu;F. Akimoto;S. Allen;N. Anabuki;L. Angelini;K. Arnaud-K.-Arn
星系团是宇宙中最大的引力束缚物体，并且仍在形成中。因此，它们是宇宙学参数和许多天体物理过程的重要探测器。然而，对弥漫的热气体的动力学知识，其质量远远大于星团中所有恒星的质量之和，是缺乏的。这些知识将使我们能够深入了解中央超大质量黑洞注入的机械能，以及利用流体静力学平衡来确定星系团质量。来自英仙座星系团核心的X射线是由充满其引力势阱的5000万开尔文弥漫热等离子体发射的。中央星系NGC 1275的活动星系核将喷射的能量泵入周围的团内介质，产生充满相对论等离子体的浮力气泡。这些气泡可能会引起星系团内介质的运动，并加热内部气体，防止失控的辐射冷却-一个被称为活动星系核反馈的过程。在这里，我们报告的X射线观测英仙座星团的核心，它揭示了一个非常安静的气氛中，气体的视线速度色散为164 ± 10公里每秒的区域30-60千秒差距的中央核。在60千秒差距的星系团核心图像上，发现了每秒150 ± 70公里的视线速度梯度。气体中的湍流压力支持是热力学压力的4%，大尺度剪切最多是这个估计的两倍。我们推断，从流体静力平衡在中心区域确定的总集群质量将需要很少的湍流压力校正。
Clusters of galaxies are the most massive gravitationally bound objects in the Universe and are still forming. They are thus important probes of cosmological parameters and many astrophysical processes. However, knowledge of the dynamics of the pervasive hot gas, the mass of which is much larger than the combined mass of all the stars in the cluster, is lacking. Such knowledge would enable insights into the injection of mechanical energy by the central supermassive black hole and the use of hydrostatic equilibrium for determining cluster masses. X-rays from the core of the Perseus cluster are emitted by the 50-million-kelvin diffuse hot plasma filling its gravitational potential well. The active galactic nucleus of the central galaxy NGC 1275 is pumping jetted energy into the surrounding intracluster medium, creating buoyant bubbles filled with relativistic plasma. These bubbles probably induce motions in the intracluster medium and heat the inner gas, preventing runaway radiative cooling—a process known as active galactic nucleus feedback,,,,. Here we report X-ray observations of the core of the Perseus cluster, which reveal a remarkably quiescent atmosphere in which the gas has a line-of-sight velocity dispersion of 164 ± 10 kilometres per second in the region 30–60 kiloparsecs from the central nucleus. A gradient in the line-of-sight velocity of 150 ± 70 kilometres per second is found across the 60-kiloparsec image of the cluster core. Turbulent pressure support in the gas is four per cent of the thermodynamic pressure, with large-scale shear at most doubling this estimate. We infer that a total cluster mass determined from hydrostatic equilibrium in a central region would require little correction for turbulent pressure.