X-Ray Spectral Properties of the Cluster Abell 2029
X-Ray Spectral Properties of the Cluster Abell 2029
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阿贝尔 2029 星团的 X 射线光谱特性
DOI：
10.1086/305578
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发表时间：
1997
期刊：
影响因子：
--
通讯作者：
M. Markevitch
中科院分区：
文献类型：
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作者：
C. Sarazin;M. Wise;M. Markevitch
我们分析了星系团Abell 2029的ASCA和ROSAT PSPC光谱和图像。星团的ASCA光谱表明，气体温度随半径的增加而降低。PSPC图像显示，集群非常规则和光滑。此外，没有明显的证据表明星团中的温度分布有任何不规则性，这可能是由子星团合并产生的。这些结果表明A2029是一个松弛的团簇，气体处于流体静力平衡状态。我们使用平衡假设来确定星团的引力质量作为半径的函数。半径为16' (1.92 h - 150 Mpc; H0 = 50 h50 km s-1 Mpc-1)，引力质量为Mtot =（9.42±4.22）× 1014 h - 150 M☉，而气体质量为Mgas =（2.52±0.77）× 1014 h - 5/250 M☉。气体分数随半径增大而增大；在16′球半径范围内，分数为Mgas/Mtot =(0.26±0.14)h−3/250。发现气体中的铁丰度为0.40±0.04太阳。没有明显的证据表明丰度随星团位置的变化而变化。整体x射线光谱、中心x射线光谱和ROSAT表面亮度都需要星团中心的冷却流。全球x射线光谱表明总冷却速率为363+ 79−96 h−250 M☉yr-1。全球x射线光谱与星系对星团的软x射线吸收值一致。White等人和Allen & Fabian认为，星系团中存在与冷却流相关的大量过量吸收。星团中心区域的ROSAT PSPC光谱与前景过量吸收的大值不一致。过量前景吸收的上限为7.3 × 1019 cm-2。然而，光谱并不排除在冷却流区内存在大量的本征吸收气体。
We have analyzed ASCA and ROSAT PSPC spectra and images of the galaxy cluster Abell 2029. The ASCA spectra of the cluster indicate that the gas temperature declines with radius. The PSPC image shows that the cluster is very regular and smooth. Also, there is no significant evidence for any irregularities in the temperature distribution in the cluster, as would be produced by a subcluster merger. These results suggest that A2029 is a relaxed cluster and that the gas is in hydrostatic equilibrium. We use the assumption of equilibrium to determine the gravitational mass of the cluster as a function of radius. At a radius of 16' (1.92 h−150 Mpc; H0 = 50 h50 km s-1 Mpc-1), the gravitational mass is Mtot = (9.42 ± 4.22) × 1014 h−150 M☉, while the mass of gas is Mgas = (2.52 ± 0.77) × 1014 h−5/250 M☉. The gas fraction is found to increase with radius; within a spherical radius of 16', the fraction is Mgas/Mtot = (0.26 ± 0.14) h−3/250 . The iron abundance in the gas is found to be 0.40 ± 0.04 solar. There is no significant evidence for any variation in the abundance with position in the cluster. The global X-ray spectra, central X-ray spectra, and ROSAT surface brightness all require a cooling flow at the cluster center. The global X-ray spectrum implies that the total cooling rate is 363+ 79−96 h−250 M☉ yr-1. The global X-ray spectra are consistent with the Galactic value for the soft X-ray absorption toward the cluster. White et al. and Allen & Fabian have suggested that there is significant excess absorption associated with the cooling flow in the cluster. The ROSAT PSPC spectra of the central regions of the cluster are inconsistent with a large value of foreground excess absorption. The upper limit on excess foreground absorption is 7.3 × 1019 cm-2. However, the spectra do not rule out a significant amount of intrinsic absorbing gas located within the cooling flow region.