Nature. 2025 Feb;638(8050):365-369. doi: 10.1038/s41586-024-08561-z. Epub 2025 Feb 12.
Galaxy clusters contain vast amounts of hot ionized gas known as the intracluster medium (ICM). In relaxed cluster cores, the radiative cooling time of the ICM is shorter than the age of the cluster. However, the absence of line emission associated with cooling suggests heating mechanisms that offset the cooling, with feedback from active galactic nuclei (AGNs) being the most likely source. Turbulence and bulk motions, such as the oscillating ('sloshing') motion of the core gas in the cluster potential well, have also been proposed as mechanisms for heat distribution from the outside of the core. Here we present X-ray spectroscopic observations of the Centaurus galaxy cluster with the X-Ray Imaging and Spectroscopy Mission satellite. We find that the hot gas flows along the line of sight relative to the central galaxy, with velocities from 130 km s to 310 km s within about 30 kpc of the centre. This indicates bulk flow consistent with core gas sloshing. Although the bulk flow may prevent excessive accumulation of cooled gas at the centre, it could distribute the heat injected by the AGN and bring in thermal energy from the surrounding ICM. The velocity dispersion of the gas is found to be only ≲120 km s in the core, even within about 10 kpc of the AGN. This suggests that the influence of the AGN on the surrounding ICM motion is limited in the cluster.
星系团包含大量被称为星系团内介质（ICM）的热电离气体。在松弛的星系团核心中，ICM的辐射冷却时间比星系团的年龄短。然而，缺乏与冷却相关的谱线发射表明存在抵消冷却的加热机制，其中活跃星系核（AGN）的反馈是最有可能的来源。湍流和整体运动，例如星系团势阱中核心气体的振荡（“晃动”）运动，也被认为是从核心外部进行热量分布的机制。在此，我们利用X射线成像和光谱任务卫星对半人马座星系团进行了X射线光谱观测。我们发现，热气体相对于中心星系沿着视线流动，在中心约30千秒差距范围内的速度为130千米每秒至310千米每秒。这表明整体流动与核心气体晃动一致。尽管整体流动可能会阻止冷却气体在中心过度积聚，但它可能会分布AGN注入的热量，并从周围的ICM引入热能。在核心区域，即使在距离AGN约10千秒差距范围内，气体的速度弥散也仅约为≲120千米每秒。这表明在星系团中，AGN对周围ICM运动的影响是有限的。
