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arXiv 0705.1444astro-ph
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Abell 115星系团的动力学状态

The dynamical status of the galaxy cluster Abell 115

R. Barrena, W. Boschin, M. Girardi, M. Spolaor

摘要:

我们提出了一个新的光谱和光度测量的结果,热,双X射线集群A115在z=0.193,包含一个无线电遗物。我们结合星系的速度和位置信息,以选择85个星系公认的集群成员(从115个星系在TNG望远镜观测),确定全球的动力学特性和检测子结构。我们发现A115的速度频散σ_v=1362_{-108}^{+126} km/s。我们的分析证实了存在两个结构(A115 N和A115 S)的集群-类型很好地识别在天空的平面,并表明,他们的视线速度相差约2000公里/秒。我们估计A115 S在动态上比A115 N稍微更重要,sigma_v=900-1100 km/s,而sigma_v=750-850 km/s。此外,我们发现两个小组在低速的证据。我们估计一个全球集团维里质量为2.2- 3.5 e 15 h 70 Msun。我们的研究结果与A115 N和A115 S以LOS碰撞速度Δ v~1600 km/s碰撞的预合并方案一致。两体问题最可能的解决方案表明合并轴位于距天空平面$\sim 20$度处,并且核心将在~0.1 Gyr后交叉。最大尺寸垂直于合并轴的射电遗迹可能与这次合并有关。

英文摘要:

We present the results of a new spectroscopic and photometric survey of the hot, binary X-ray cluster A115 at z=0.193, containing a radio relic. We combine galaxy velocity and position information to select 85 galaxies recognized as cluster members (from 115 galaxies observed at TNG telescope), determine global dynamical properties and detect substructures. We find that A115 presents velocity dispersion of sigma_v=1362_{-108}^{+126} km/s. Our analysis confirms the presence of two structures (A115N and A115S) of cluster--type well recognizable in the plane of the sky and shows that they differ of ~2000 km/s in the LOS velocity. We estimate that A115S is slightly dynamically more important than A115N having sigma_v=900-1100 km/s vs sigma_v=750-850 km/s. Moreover, we find evidence for two small groups at low velocities. We estimate a global cluster virial mass of 2.2--3.5 e15 h_70 Msun. Our results agree with a pre--merging scenario where A115N and A115S are colliding with a LOS impact velocity Delta v~1600 km/s.The most likely solution to the two--body problem suggests that the merging axis lies at $\sim 20$ degrees from the plane of the sky and that the cores will cross after ~0.1 Gyr. The radio relic with its largest dimension perpendicular to the merging axis is likely connected to this merger.

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