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arXiv 0711.3908astro-ph
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A1689中的质量和气体分布:联合X射线和透镜分析

Mass and Gas Profiles in A1689: Joint X-ray and Lensing Analysis

Doron Lemze, Rennan Barkana, Tom J. Broadhurst, Yoel Rephaeli

摘要:

我们对A1689的高质量HST/ACS和Chandra测量进行了全面的联合分析,从中我们获得了质量,温度,X射线发射和丰度分布。X射线发射是平滑和对称的,并且透镜质量集中在中心,指示松弛的集群。假设流体静力平衡,我们推导出一个三维质量分布,同时同意与透镜和X射线测量。然而,预测与此3D质量分布预测的温度分布超过观察到的温度在所有半径的~30%,一个水平的差异相比,发现其他松弛集群的水平。这一结果可能支持流体动力学模拟的最新建议,即密度更大、更X射线发光的小尺度结构可以使观察到的温度测量值向下偏移大约相同(约30%)的水平。我们确定了在0.1 r_{vir}(其中r_{vir}是维里半径)处的气体熵约为800 keV cm ^2,正如对高温星系团的预期,但在>0.1 r_{vir}处的分布具有指数约为0.8的幂律形式,比理论研究和模拟所提倡的指数约为1.1要浅得多。此外,如果一个恒定的熵“地板”存在,那么它是在内核的一个小区域内,r<0.02 r_{vir},与以前的大质量星系团的理论研究一致。

英文摘要:

We carry out a comprehensive joint analysis of high quality HST/ACS and Chandra measurements of A1689, from which we derive mass, temperature, X-ray emission and abundance profiles. The X-ray emission is smooth and symmetric, and the lensing mass is centrally concentrated indicating a relaxed cluster. Assuming hydrostatic equilibrium we deduce a 3D mass profile that agrees simultaneously with both the lensing and X-ray measurements. However, the projected temperature profile predicted with this 3D mass profile exceeds the observed temperature by ~30% at all radii, a level of discrepancy comparable to the level found for other relaxed clusters. This result may support recent suggestions from hydrodynamical simulations that denser, more X-ray luminous small-scale structure can bias observed temperature measurements downward at about the same (~30%) level. We determine the gas entropy at 0.1r_{vir} (where r_{vir} is the virial radius) to be ~800 keV cm^2, as expected for a high temperature cluster, but its profile at >0.1r_{vir} has a power-law form with index ~0.8, considerably shallower than the ~1.1 index advocated by theoretical studies and simulations. Moreover, if a constant entropy ''floor'' exists at all, then it is within a small region in the inner core, r<0.02r_{vir}, in accord with previous theoretical studies of massive clusters.

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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