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双激波星系团Abell 4067的钱德拉观测

The Chandra Observation of the Double-Shock Galaxy Cluster Abell 4067

  • 摘要: 对动态复杂的星系团Abell 4067 (A4067、z = 0.0992)使用钱德拉X射线空间望远镜观测, 研究发现A4067是一个由致密的子星系团在东西轴向上与一个较大的弥散星系团并合形成的结构, 其中子星系团核心温度约为1.37 keV, 主星系团平均温度约为2.44 keV. X射线成像和光谱分析显示, A4067存在包括表面亮度不连续性在内的复杂结构, 这表明A4067正在经历合并活动. 从X射线表面亮度的径向分布图和温度分布图中观测到3个表面亮度边缘, 其中一个是星系团并合产生的冷锋, 另外两个为并合激波. 两个并合激波分别位于星系团东侧和西侧, 这表明A4067很可能是具有双激波并合结构的罕见源. 结合东侧激波SF1的性质估算出A4067并合的时间尺度约(0.51 ± 0.01) Gyr, 这表明星系团正在并合中期. 此外还结合冷锋马赫数, 估算区域磁场下限大约在 7.17 \times 10^-6 Gs. A4067的动力学结构符合小致密星系团与大弥散星系团的东西并合模型, 类似子弹星系团的并合结构.

     

    Abstract: Observations of the dynamically complex galaxy cluster Abell 4067 (A4067; z = 0.0992) were carried out using the Chandra X-ray Observatory (CXO). The study identifies a merger structure wherein a compact subcluster is coalescing with a more extended, diffuse cluster along the east-west axis. The core temperature of the subcluster is approximately 1.37 keV, while the mean temperature of the primary cluster is about 2.44 keV. X-ray imaging and spectral analysis reveal intricate structures, including surface brightness discontinuities, indicative of an ongoing merger event. The radial profiles of X-ray surface brightness and temperature distributions reveal three distinct surface brightness edges, one of which corresponds to a merger-driven cold front, while the other two are associated with merger shocks. These shocks, located on the eastern and western peripheries of the cluster, suggest that A4067 is a rare system exhibiting a dual-shock merger morphology. Based on the properties of the eastern shock SF1, the article estimates the merger timescale of A4067 to be approximately \left(0.51\pm0.01\right)\, \rmGyr , suggesting that the system is in the intermediate stage of the merger process. Additionally, leveraging the Mach number of the cold front, the article derives a lower bound on the intracluster magnetic field strength of approximately 7.17 \times 10^-6 Gs. The dynamical configuration of A4067 aligns with a scenario involving the merger of a compact subcluster with a more massive, diffuse cluster along the east-west axis, resembling the archetypal Bullet Cluster merger.

     

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