arXivDaily arXiv每日学术速递 周一至周五更新
北美退伍军人节(Veterans Day),12 日无更新
arXiv 1504.02708astro-ph.HEastro-ph.COastro-ph.GA
收藏

发现附近的早期主要集群合并CIZA J1358. 9 -4750

Discovery of a nearby early-phase major cluster merger CIZA J1358.9-4750

Yuichi Kato, Kazuhiro Nakazawa, Liyi Gu, Takuya Akahori, Motokazu Takizawa, Yutaka Fujita, Kazuo Makishima

摘要:

CIZA J1358.9-4750是一对靠近银河平面的星系团。它由两个X射线延伸的驼峰组成,分别位于西北和东南方向,相距14弧分(约1.2 Mpc),中间有一个X射线亮桥状结构。在朱雀星上,东南驼峰的温度为5.6 keV,西北驼峰的温度为4.6 keV。两个驼峰都没有表现出明显的中央冷分量。桥区域的温度高于9千电子伏的最大值,这个热的区域分布几乎正交的桥梁轴在协议的冲击加热数值模拟中看到的早期阶段的迎面大合并。这种相似性得到了X射线峰和与每个星系团相关的cD星系之间良好位置重合的支持。在短曝光XMM-牛顿图像中,在Suzaku测量的温度呈现陡峭梯度的位置处发现显著的强度跳跃。这些特性表明存在激波间断。根据确定的激波阵面两侧的温度差,估算出的马赫数为1.32,碰撞速度约为1800 km/s。从成员星系的光学红移来看,这两个星系团几乎在天球平面上合并。因此,CIZA J1358.9-4750被认为是具有明显激波特征的早期合并的有价值的邻近例子。

英文摘要:

CIZA J1358.9-4750 is a nearby (z = 0.074) pair of clusters of galaxies located close to the Galactic plane. It consists of two X-Ray extended humps at north-west and south-east separated by 14 arcmin (~ 1.2 Mpc), and an X-Ray bright bridge-like structure in between. With Suzaku, the south-east hump was shown to have a temperature of 5.6 keV and the north-west one 4.6 keV. Neither humps exhibit significant central cool component. The bridge region has a temperature higher than 9 keV at the maximum, and this hot region is distributed almost orthogonal to the bridge axis in agreement with the shock heating seen in numerical simulations at an early phase of a head-on major merger. This resemblance is supported by good positional coincidence between the X-Ray peaks and cD galaxies associated with each cluster. In a short exposure XMM-Newton image, a significant intensity jump was found at a position where the Suzaku-measured temperature exhibits a steep gradient. These properties indicate the presence of a shock discontinuity. The Mach number is estimated to be 1.32 from the temperature difference across the identified shock front, which gives the colliding velocity of approximately 1800 km/s. From optical redshifts of the member galaxies, the two clusters are indicated to be merging nearly on the sky plane. Thus, CIZA J1358.9-4750 is considered as a valuable nearby example of early-phase merger with a clear shock feature.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

↑