Galaxy Cluster Mass Estimates in the Presence of Substructure
Galaxy Cluster Mass Estimates in the Presence of Substructure
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DOI：
10.3847/1538-4357/ab609d
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发表时间：
2018-10
期刊：
影响因子：
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通讯作者：
E. Tucker;M. Walker;M. Mateo;E. Olszewski;A. Geringer-Sameth;C. Miller
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文献类型：
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作者：
E. Tucker;M. Walker;M. Mateo;E. Olszewski;A. Geringer-Sameth;C. Miller
我们开发并实现了一个模型来分析星系团的内部运动学，可能包含不独立跟踪集群潜力的星系子群。该模型允许在集群环境的子结构和解开集群成员污染的前景和背景星系。我们估计集群的速度分散和/或质量，同时边缘化在所有上述复杂性的不确定性。使用MultiDark模拟的模拟观察，我们将模拟的真实子结构与我们模型识别的子结构进行比较，结果表明，50%的识别子结构至少有79%的成员也是同一真实子结构的成员，这与其他子结构识别算法相当。此外，我们显示了一个35%的减少，在散射的推断速度色散与真实的集群质量的关系时，比较模型，允许三个子结构的模型，假设没有子结构。在我们公布的A267数据的第一个应用程序中，我们确定了四个不同的星系亚群。我们使用这些结果来探索推断集群属性的敏感性的子结构的治疗。与假设没有子结构的模型相比，我们的子结构模型将A267的动力学质量减少了22%，并将星系团的平均速度移动了100 km/s，大约是A267最亮星系团速度的两倍。在这个框架内嵌入球形的金斯方程，我们推断A267的晕质量M200 =（7.0 ± 1.3）× 1014 M h−1和浓度，与宇宙学模拟中发现的质量-浓度关系一致。
We develop and implement a model to analyze the internal kinematics of galaxy clusters that may contain subpopulations of galaxies that do not independently trace the cluster potential. The model allows for substructures within the cluster environment and disentangles cluster members from contaminating foreground and background galaxies. We estimate the cluster velocity dispersion and/or mass while marginalizing over uncertainties in all of the above complexities. Using mock observations from the MultiDark simulation, we compare the true substructures from the simulation with the substructures identified by our model, showing that 50% of the identified substructures have at least 79% of its members are also members of the same true substructure, which is on par with other substructure identification algorithms. Furthermore, we show a ∼35% decrease in scatter in the inferred velocity dispersion versus true cluster mass relationship when comparing a model that allows three substructures to a model that assumes no substructure. In a first application to our published data for A267, we identify up to four distinct galaxy subpopulations. We use these results to explore the sensitivity of inferred cluster properties to the treatment of substructure. Compared to a model that assumes no substructure, our substructure model reduces the dynamical mass of A267 by ∼22% and shifts the cluster mean velocity by ∼100 km s−1, approximately doubling the offset with respect to the velocity of A267's brightest cluster galaxy. Embedding the spherical Jeans equation within this framework, we infer for A267 a halo mass M200 = (7.0 ± 1.3) × 1014 M⊙ h−1 and concentration , consistent with the mass–concentration relation found in cosmological simulations.