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arXiv 1810.00525astro-ph.HE
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低表面亮度星系团Abell 2399的高熵和合并证据

High entropy and evidence for a merger in the low surface brightness cluster Abell 2399

Ikuyuki Mitsuishi, Yasunori Babazaki, Naomi Ota, Shin Sasaki, Hans Bohringer, Gayoung Chon, Gabriel W. Pratt

摘要:

本文介绍了利用XMM-牛顿和朱雀卫星对邻近星系团Abell 2399($z=0.058$)进行X射线分析的结果。该集群被分类为低表面亮度(LSB)集群。它在X射线中具有双峰结构,并且X射线发射峰与气体温度峰显著偏移。通过对环形谱的去投影,测得中心$r<0.1r_{200}$区的温度和电子密度分别为3.6 keV和$1.4\times10^{-3}~{\rm cm^{-3}}$。这在中心区域产生了非常高的气体熵,$\sim 300~{\rm keV\,cm^{2}}$,与在其他LSB集群中观察到的值相当。Abell 2399的标度熵是REXCESS聚类样本中最高的。成员星系的空间分布表现出多重的亚结构,其位置与X射线图像中的位置有很大的不同。我们发现西部气团的X射线亮度和温度分布存在明显的不连续性,这为冷锋的存在提供了证据。因此,我们的研究结果强烈地表明,A2399已经经历了合并和高中心熵起源于合并活动。

英文摘要:

We present results of the X-ray analyses of the nearby cluster of galaxies Abell 2399 ($z=0.058$) using the XMM-Newton and Suzaku satellites. This cluster is classified as a low surface brightness (LSB) cluster. It has a bimodal structure in X-rays, and the X-ray-emission peaks are significantly offset from the peaks in gas temperature. By de-projecting the annular spectra, the temperature and electron density in the central $r<0.1r_{200}$ region are measured to be 3.6~keV and $1.4\times10^{-3}~{\rm cm^{-3}}$, respectively. This yields a very high gas entropy, $\sim 300~{\rm keV\,cm^{2}}$, in the central region, comparable to the values observed in other LSB clusters. The scaled entropy of Abell 2399 is the highest among the REXCESS cluster sample. The spatial distribution of the member galaxies exhibits multiple substructures, the locations of which are significantly different from those in the X-ray image. We discovered a clear discontinuity in the X-ray brightness and temperature distributions in the western gas clump, which provides evidence of the presence of a cold front. Therefore, our results strongly suggest that A2399 has experienced a merger and that the high central entropy originates from the merger activity.

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。

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