论文标题
结合FOF和基于光晕的算法以识别星系基团
Combining FOF and halo-based algorithms for the identification of galaxy groups
论文作者
论文摘要
银河系为大量研究提供了一种手段，这些研究有助于更好地理解大规模的宇宙结构，并允许星系的性质与宿主光晕的特性相关。但是，识别星系系统是一项具有挑战性的任务，因此有必要尽可能提高所涉及的技术。鉴于当前和即将出现的银河系目录，我们建议，实施和评估一种结合了用于识别星系系统的两种最受欢迎的技术的算法。该算法可以轻松地应用于任何光谱星系目录，但在这里我们在Sloan Digital Sky调查中证明了它的用途。假设星系组是一个具有至少一个明亮星系的重力系统，我们首先要识别具有适合此定义的朋友的朋友算法的组。鉴于这种方法的缺点，尤其是缺乏识别低数字群体的能力，因此无法研究整个质量范围内的光晕的职业，我们通过添加基于光晕的程序来改进它。为了评估性能，我们从半分析模型中构建了模拟目录，以比较使用我们的方法识别的组与从模拟获得的组进行比较。使用我们方法提取的组与模拟目录的组进行比较表明，所提出的算法可提供出色的结果。在该程序的第一部分中，介绍了合适的朋友算法的修改，以适合所采用的小组定义，从而提供了可靠的小组。此外，基于光晕的方法的掺入会减少撞车器，同时更准确地重现每组星系的数量。作为特定应用，我们使用算法从斯隆数字天空调查中提取组。
Galaxy groups provide the means for a great diversity of studies that contribute to a better understanding of the structure of the universe on a large scale and allow the properties of galaxies to be linked to those of the host halos. However, the identification of galaxy systems is a challenging task and therefore it is necessary to improve the techniques involved as much as possible. In view of the large present and forthcoming galaxy catalogues, we propose, implement, and evaluate an algorithm that combines the two most popular techniques used to identify galaxy systems. The algorithm can be easily applied to any spectroscopic galaxy catalogue, but here we demonstrate its use on the Sloan Digital Sky Survey. Assuming that a galaxy group is a gravitationally bounded system that has at least one bright galaxy, we begin by identifying groups with a Friends-Of-Friends algorithm adapted to fit this definition. In view of the shortcomings of this method, particularly the lack of ability to identify low-number groups, and consequently the inability to study the occupation of halos throughout the mass range, we improve it by adding a halo-based procedure. To assess the performance, we construct a mock catalogue from a semi-analytical model to compare the groups identified using our method with those obtained from the simulation. The comparison of groups extracted using our method with those of a mock catalogue shows that the proposed algorithm provides excellent results. The modifications introduced to the Friends-Of-Friends algorithm in the first part of the procedure to fit the adopted group definition gave reliable groups. Furthermore, the incorporation of the halo-based method reduces the interlopers while more accurately reproducing the number of galaxies per group. As a specific application, we use the algorithm to extract groups from the Sloan Digital Sky Survey.
