论文标题
相关性在2D和3D中作为宇宙Web的描述符
Correlation functions in 2D and 3D as descriptors of the cosmic web
论文作者
论文摘要
目标。我们的目标是在宇宙Web的上下文中找到星系的投影和空间密度场的两点相关函数（CFS）之间的关系。方法。为了研究星系的空间（3D）与预测的（2D）CF之间的关系，我们使用了两个模拟的密度字段：具有已知粒子数据的$λ$二世二世冷的暗物质（LCDM）模型，以及具有模拟星系的数据。我们比较3D和2D相关函数。在2D情况下，我们使用各种厚度的样品来找到2D CFS对样品厚度的依赖性。我们还比较了实际和红移空间中的3D CFS。结果。宇宙网络的主要元素是簇和细丝，由填充大部分体积的空隙隔开。在单个2D纸中，簇和细丝的位置不一致。结果，在投影中，簇和细丝填充了2D空隙。这导致投影中CFS（和功率谱）的振幅减少。因此，2D CF的幅度低于3D相关函数的振幅：厚度越厚，差异越大。结论。星系的空间CF包含有关宇宙网络几何特性的有价值信息，这些信息从投影的CFS中找不到。
Aims. Our goal is to find the relation between the two-point correlation functions (CFs) of projected and spatial density fields of galaxies in the context of the cosmic web. Methods. To investigate relations between spatial (3D) and projected (2D) CFs of galaxies we used density fields of two simulations: a $Λ$-dominated cold dark matter (LCDM) model with known particle data, and the Millennium simulation with know data on simulated galaxies. We compare 3D and 2D correlation functions. In the 2D case, we use samples of various thickness to find the dependence of 2D CFs on the thickness of samples. We also compare 3D CFs in real and redshift space. Results. The dominant elements of the cosmic web are clusters and filaments, separated by voids filling most of the volume. In individual 2D sheets, the positions of clusters and filaments do not coincide. As a result, in projection, the clusters and filaments fill in 2D voids. This leads to a decrease in the amplitudes of CFs (and power spectra) in projection. For this reason, the amplitudes of 2D CFs are lower than the amplitudes of 3D correlation functions: the thicker the 2D sample, the greater the difference. Conclusions. Spatial CFs of galaxies contain valuable information about the geometrical properties of the cosmic web that cannot be found from projected CFs.
