Zhang Yikun, de Souza Rafael S, Chen Yen-Chi
Department of Statistics, University of Washington, Seattle, WA 98195, USA.
Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030, China.
Mon Not R Astron Soc. 2022 Oct 8;517(1):1197-1217. doi: 10.1093/mnras/stac2504. eCollection 2022 Nov.
The latticework structure known as the cosmic web provides a valuable insight into the assembly history of large-scale structures. Despite the variety of methods to identify the cosmic web structures, they mostly rely on the assumption that galaxies are embedded in a Euclidean geometric space. Here, we present a novel cosmic web identifier called sconce (pherical and ic osmic wb finder) that inherently considers the 2D (RA, DEC) spherical or the 3D (RA, DEC, ) conic geometry. The proposed algorithms in sconce generalize the well-known subspace constrained mean shift (scms) method and primarily address the predominant filament detection problem. They are intrinsic to the spherical/conic geometry and invariant to data rotations. We further test the efficacy of our method with an artificial cross-shaped filament example and apply it to the SDSS galaxy catalogue, revealing that the 2D spherical version of our algorithms is robust even in regions of high declination. Finally, using -body simulations from Illustris, we show that the 3D conic version of our algorithms is more robust in detecting filaments than the standard scms method under the redshift distortions caused by the peculiar velocities of haloes. Our cosmic web finder is packaged in python as sconce-scms and has been made publicly available.
被称为宇宙网的晶格结构为深入了解大规模结构的组装历史提供了有价值的见解。尽管有多种识别宇宙网结构的方法，但它们大多依赖于星系嵌入欧几里得几何空间的假设。在此，我们提出一种名为sconce（球面和圆锥宇宙网探测器）的新型宇宙网识别器，它本质上考虑了二维（赤经，赤纬）球面或三维（赤经，赤纬，红移）圆锥几何。sconce中提出的算法推广了著名的子空间约束均值漂移（scms）方法，并主要解决了主要的细丝检测问题。它们对于球面/圆锥几何是内在的，并且对数据旋转是不变的。我们还用一个人工十字形细丝示例进一步测试了我们方法的有效性，并将其应用于斯隆数字巡天星系目录，结果表明我们算法的二维球面版本即使在高赤纬区域也很稳健。最后，使用Illustris的N体模拟，我们表明在晕的特殊速度引起的红移扭曲下，我们算法的三维圆锥版本在检测细丝方面比标准scms方法更稳健。我们的宇宙网探测器以sconce - scms的形式打包在python中并已公开可用。
