Ram pressure stripping of the cool core of the Ophiuchus Cluster
Ram pressure stripping of the cool core of the Ophiuchus Cluster
复制标题
蛇夫座星团冷核的冲压压力剥离
DOI：
10.1111/j.1365-2966.2010.16596.x
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
G. Taylor
中科院分区：
文献类型：
--
作者：
E. Million;E. Million;S. Allen;S. Allen;N. Werner;N. Werner;G. Taylor
我们报告了钱德拉对附近的中心区域的研究结果，X射线明亮，蛇夫座星系团（z = 0.03），天空中第二亮的星系团。我们的研究揭示了一个戏剧性的，特写镜头的剥离和潜在的破坏一个冷核心内丰富的集群。蛇夫座星系团核心的X射线辐射呈现出向北延伸的彗星状形态，这是由合并活动驱动的，表明快速运动通过周围的星系团气体造成的冲压压力剥离。在南部边缘的冷锋意味着1000200 km/s（M~0.6）的速度。来自星系团核心的X射线辐射是尖锐的峰值。如前所述，峰值与相关cD星系的光学中心偏移了4角秒（约2千秒差距），表明冲压压力减缓了核心，使相对无碰撞的恒星和暗物质继续前进。该星团的中心温度梯度是迄今为止观测到的最强的：在亮度峰值1千秒差距内，温度从0.7千电子伏上升到30千秒差距内的10千电子伏。在同一区域内也观察到了很强的金属丰度梯度。这支持了这样一种观点，即冷核的外部部分由于其快速运动而被冲压压力剥离。最内层气体的冷却时间非常短，约为50 × 107 $yrs。在中心10 kpc半径范围内，观察到多个小尺度锋和复杂的热力学结构，表明有显著的运动。超过中心50 kpc，半径约150 kpc，集群似乎相对等温，并有接近恒定的金属丰度。唯一的例外是一个大型的、连贯的、金属丰度增强的脊，它被观察到跟踪在冷核的后面，很可能是从冷核中剥离出来的。
(abridged) We report results from a Chandra study of the central regions of the nearby, X-ray bright, Ophiuchus Cluster (z = 0.03), the second-brightest cluster in the sky. Our study reveals a dramatic, close-up view of the stripping and potential destruction of a cool core within a rich cluster. The X-ray emission from the Ophiuchus Cluster core exhibits a comet-like morphology extending to the north, driven by merging activity, indicative of ram-pressure stripping caused by rapid motion through the ambient cluster gas. A cold front at the southern edge implies a velocity of 1000$\pm$200 km/s (M~0.6). The X-ray emission from the cluster core is sharply peaked. As previously noted, the peak is offset by 4 arcsec (~2 kpc) from the optical center of the associated cD galaxy, indicating that ram pressure has slowed the core, allowing the relatively collisionless stars and dark matter to carry on ahead. The cluster exhibits the strongest central temperature gradient of any massive cluster observed to date: the temperature rises from 0.7 keV within 1 kpc of the brightness peak, to 10 keV by 30 kpc. A strong metallicity gradient is also observed within the same region. This supports a picture in which the outer parts of the cool core have been stripped by ram-pressure due to its rapid motion. The cooling time of the innermost gas is very short, ~5$\times10^7$ yrs. Within the central 10 kpc radius, multiple small-scale fronts and a complex thermodynamic structure are observed, indicating significant motions. Beyond the central 50 kpc, and out to a radius ~150 kpc, the cluster appears relatively isothermal and has near constant metallicity. The exception is a large, coherent ridge of enhanced metallicity observed to trail the cool core, and which is likely to have been stripped from it.