提高在投影相空间图（Projected Phase Space Diagram）中分类星系的可观测分布的准确性
Improving the accuracy of observable distributions for galaxies classified in the Projected Phase Space Diagram
AI总结：
针对PPSD星系分类中的误分类污染，本文基于MultiDark Planck 2与SAG模拟构建并求逆混淆矩阵，显著改进星系团成员、回溅星系和近期落入者的质量依赖颜色分布估计。
摘要：
利用投影相空间图（PPSD）并根据星系的运动学行为和动力学状态对星系族群进行分类的研究，会受到误分类和污染的影响，从而在确定不同星系类别特征时导致系统误差。我们提出一种统计校正星系属性分布测定的方法，该方法考虑了来自其他类别的误分类星系所造成的污染。利用取自 MultiDark Planck 2 模拟并结合星系形成半解析模型 SAG 的大质量星系团及其周围星系样本，我们计算了与 PPSD 中一种分类方案相关的混淆矩阵。根据在 PPSD 中的位置，星系被分类为星系团成员、回溅星系、近期落入者、正在落入星系和闯入者。该分类使用代码 ROGER 计算的概率以及阈值准则来确定。通过对混淆矩阵求逆，我们能够更好地测定颜色等星系属性的分布。与仅基于预测星系类别的直接估计相比，对于受误分类影响最大的星系类别——星系团成员、回溅星系和近期落入者，我们的方法对其依赖于质量的颜色分布给出了更好的估计。我们将该方法应用于一个观测到的 X 射线星系团和星系样本。只要能够估计混淆矩阵，我们的方法就可应用于 PPSD 中星系的任何分类，也可应用于除颜色之外的任何其他星系属性。星系团中蓝色、低质量星系几乎完全是尚未被星系团环境作用淬灭的近期落入星系。回溅星系平均而言比预期更红。
英文摘要：
Studies of galaxy populations classified according to their kinematic behaviours and dynamical state using the Projected Phase Space Diagram (PPSD) are affected by misclassification and contamination, leading to systematic errors in determining the characteristics of the different galaxy classes. We propose a method to statistically correct the determination of galaxy properties' distributions accounting for the contamination caused by misclassified galaxies from other classes. Using a sample of massive clusters and galaxies in their surroundings taken from the MultiDark Planck 2 simulation combined with the semi-analytic model of galaxy formation SAG, we compute the confusion matrix associated to a classification scheme in the PPSD. Based on positions in the PPSD, galaxies are classified as cluster members, backsplash galaxies, recent infallers, infalling galaxies, and interlopers. This classification is determined using probabilities calculated by the code ROGER, along with a threshold criterion. By inverting the confusion matrix, we are able to get better determinations of distributions of galaxy properties such as colour. Compared to a direct estimation based solely on the predicted galaxy classes, our method provides better estimates of the mass-dependent colour distribution for the galaxy classes most affected by misclassification: cluster members, backsplash galaxies, and recent infallers. We apply the method to a sample of observed X-ray clusters and galaxies. Our method can be applied to any classification of galaxies in the PPSD, and to any other galaxy property besides colour, provided an estimation of the confusion matrix. Blue, low-mass galaxies in clusters are almost exclusively recent infaller galaxies that have not yet been quenched by the environmental action of the cluster. Backsplash galaxies are on average redder than expected.
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