Large-scale inhomogeneities of the intracluster medium: improving mass estimates using the observed azimuthal scatter
Large-scale inhomogeneities of the intracluster medium: improving mass estimates using the observed azimuthal scatter
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簇内介质的大规模不均匀性：使用观察到的方位角散射改进质量估计
DOI：
10.1093/mnras/stt654
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发表时间：
2013
影响因子：
4.8
通讯作者：
L. Moscardini
中科院分区：
文献类型：
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作者：
M. Roncarelli;S. Ettori;S. Borgani;K. Dolag;D. Fabjan;L. Moscardini
为了测量其重子含量并将其用作宇宙学探测器，对星团外围的气体密度剖面进行可靠的确定是至关重要的。获得这种测量的困难不仅在于 ICM 的表面亮度低，而且还在于与团块、不对称和吸积模式相关的气体的不均匀性。通过对 62 个星系团和星系群进行一组流体动力学模拟，我们研究了这种不均匀性，重点关注大尺度上的不均匀性，这些不均匀性与星系团不同，是最难识别的。为此，我们引入了残余团块 CR 的概念，它量化了 ICM 的大规模不均匀性。在证明这个量可以为松弛系统稳健地定义之后，我们描述了它如何随晕圈的半径、质量和动力学状态变化。最重要的是，我们观察到，它在确定 X 射线发射的密度剖面时引入了高估，这意味着我们的松弛（扰动）簇样本在 R200 处的 Mgas 测量中系统性高估了 6 (12)%。与此同时，CR 随半径的增加也会导致流体静力平衡质量 (Mhe) 的测量系统性低估 2%，这使得之前的结果在我们的松弛样本中产生了 8.5% 的系统性高估。由于 ICM 的残余团块无法直接观察到，因此我们研究了它与光环 X 射线表面亮度中的方位角散射的相关性，该量受到当前测量的良好约束，并且在即将进行的 SZ 实验中可以达到 y 参数轮廓。我们发现它们的相关性非常显着（rS = 0.6 0.7），允许将 X 射线表面亮度分布和 y 参数中测量的方位角散射定义为 CR 的稳健代理。在提供连接这两个量的函数后，我们发现使用方位角散射校正观测到的气体密度分布可以消除松弛物体 Mgas 测量中的偏差，在 2R200 之前变为 0 ± 2%，而对于扰动物体则将其减少 3 倍。该方法还允许消除 Mhe 和 fgas 测量的系统性，尽管仍然存在显着的晕圈到晕圈散射。
Achieving a robust determination of the gas density profile i n cluster outskirts is a crucial point in order to measure their baryonic content and to use them as cosmological probes. The difficulty in obtaining this measurement lies not only in the low surface brightness of the ICM, but also in the inhomogeneities of the gas associated to clumps, asymmetries and accretion patterns. Using a set of hydrodynamical simulations of 62 galaxy clusters and groups we study this kind of inhomogeneities, focusing on the ones on the large scale that, unlike clumps, are the most difficult to identify. To this purpose we introduce the concept of residual clumpiness, CR, that quantifies the large-scale inhomogeneity of the ICM. A fter showing that this quantity can be robustly defined for relaxed systems, we characterize how it varies with radius, mass and dynamical state of the halo. Most importantly, we observe that it introduces an overestimate in the determination of the density profile f rom the X-ray emission, which translates into a systematic overestimate of 6 (12) per cent in the measurement of Mgas at R200 for our relaxed (perturbed) cluster sample. At the same time, the increase of CR with radius introduces also a �2 per cent systematic underestimate in the measurement of the hydrostatic-equilibrium mass (Mhe), which adds to the previous one generating a systematic �8.5 per cent overestimate in fgas in our relaxed sample. Since the residual clumpiness of the ICM is not directly observable, we study its correlation with the azimuthal scatter in the X-ray surface brightness of the halo, a quantity that is well -constrained by current measurements, and in the y-parameter profiles that is at reach of the forthcoming SZ exp eriments. We find that their correlation is highly significant ( rS = 0.6 0.7), allowing to define the azimuthal scatter measured in the X-ray surface brightness profile and in the y-parameter as robust proxies of CR. After providing a function that connects the two quantitie s, we obtain that correcting the observed gas density profiles using the a zimuthal scatter eliminates the bias in the measurement of Mgas for relaxed objects, which becomes 0 ± 2 per cent up to 2R200, and reduces it by a factor of 3 for perturbed ones. This method allows also to eliminate the systematics on the measurements of Mhe and fgas, although a significant halo to halo scatter remains.
DOI：
10.1111/j.1365-2966.2011.19523.x
发表时间：
2011-07
影响因子：
4.8
作者：
A. Bonafede;K. Dolag;F. Stasyszyn;G. Murante;S. Borgani
通讯作者：
A. Bonafede;K. Dolag;F. Stasyszyn;G. Murante;S. Borgani
簇内介质中气体团簇的性质和气体团簇因子
影响因子：
4.8
作者：
Eckert;Simionescu;Brüggen;Ettori
通讯作者：
Ettori
使用 APEX-SZ 测辐射热计成像数据对簇内气体进行非参数建模
影响因子：
6.5
作者：
通讯作者：
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