Hydrostatic Chandra X-ray analysis of SPT-selected galaxy clusters – I. Evolution of profiles and core properties
Hydrostatic Chandra X-ray analysis of SPT-selected galaxy clusters – I. Evolution of profiles and core properties
复制标题
SPT 选择的星系团的静水钱德拉 X 射线分析 – I. 轮廓和核心特性的演化
DOI：
10.1093/mnras/stx2796
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发表时间：
2017
影响因子：
4.8
通讯作者：
NasaGsfc
中科院分区：
文献类型：
--
作者：
J. Sanders;A. Fabian;H. Russell;S. A. W. Mpe;Ioa;NasaGsfc
我们分析了钱德拉X射线天文台观测的一组星系团选定的南极望远镜使用一个新的公开的前向建模投影代码，MBProj 2，假设流体静力平衡。通过拟合幂律加常数熵模型，我们发现没有证据表明在最低熵系统中存在中心熵地板。中心熵分布的模型显示出一个接近于零熵的窄峰，占系统的60%，以及第二个更宽的峰，约为130 keV cm ^2。我们期待在0.015 R_500和10 kpc半径的密度，压力，熵和冷却时间的样品在0.28至1.2的红移范围内的演变。通过用一个简单的模型模拟中心量的演化，我们没有发现红移的非零斜率的证据。此外，非参数滑动中位数显示无显著变化。中心冷却时间低于2 Gyr的冷核团簇的比例在z=0.6以上和以下是一致的（约30- 40%）。通过比较中位热力学配置文件，集中偏向冷的核心，在两个红移箱，并通过建模的无偏平均配置文件的红移函数的演变，我们发现没有显着的演变超出自相似缩放在我们的任何检查量。我们的平均模拟径向密度，熵和冷却时间的配置文件出现的幂律与休息约0.2 R_500。这些量的离散度在该半径内上升到约0.4 dex，尽管其中一些离散度可以通过双峰模型来拟合。
We analyse Chandra X-ray Observatory observations of a set of galaxy clusters selected by the South Pole Telescope using a new publicly-available forward-modelling projection code, MBProj2, assuming hydrostatic equilibrium. By fitting a powerlaw plus constant entropy model we find no evidence for a central entropy floor in the lowest-entropy systems. A model of the underlying central entropy distribution shows a narrow peak close to zero entropy which accounts for 60 per cent of the systems, and a second broader peak around 130 keV cm^2. We look for evolution over the 0.28 to 1.2 redshift range of the sample in density, pressure, entropy and cooling time at 0.015 R_500 and at 10 kpc radius. By modelling the evolution of the central quantities with a simple model, we find no evidence for a non-zero slope with redshift. In addition, a non-parametric sliding median shows no significant change. The fraction of cool-core clusters with central cooling times below 2 Gyr is consistent above and below z=0.6 (~30-40 per cent). Both by comparing the median thermodynamic profiles, centrally biased towards cool cores, in two redshift bins, and by modelling the evolution of the unbiased average profile as a function of redshift, we find no significant evolution beyond self-similar scaling in any of our examined quantities. Our average modelled radial density, entropy and cooling-time profiles appear as powerlaws with breaks around 0.2 R_500. The dispersion in these quantities rises inwards of this radius to around 0.4 dex, although some of this scatter can be fit by a bimodal model.