标题： 晕族际侵入者在投影相空间中的普遍分布。 星系团浓度和速度各向异性中的偏差？ 显示英文标题

标题： The universal distribution of halo interlopers in projected phase space. Bias in galaxy cluster concentration and velocity anisotropy?

摘要： 当星系团在投影中被观测时，不可避免地会拾取到前景/背景闯入者（FBIs），它们位于引力暴时锥（VC）内，但位于引力暴球之外。对于一个膨胀的宇宙，结构和运动学去投影方程尚不清楚，因为哈勃流（HF）拉伸了视线（LOS）上的速度分布。我们分析了由宇宙学模拟构建的93个模拟松弛星系团。堆叠的模拟星系团可以用m=5的Einasto暗物质密度剖面很好地拟合（但仅限于1.5倍引力暴半径[r_v]范围内），其速度各向异性（VA）接近Mamon-Lokas模型，且VA半径等于密度斜率-2处的半径。FBIs的表面密度在r_v范围内几乎平坦，而它们的LOS速度分布显示出一个主要的高斯星系团外围分量和平坦场分量。这种FBIs在投影相空间中的分布在质量上几乎是普遍的。局部k=2.7sigma速度切割返回了预期来自NFW密度和VA剖面的LOS速度弥散剖面（LOSVDP）。哈勃流导致了一个较浅的外层LOSVDP，任何k值下都无法很好地匹配Einasto模型。在这种速度切割之后，FBIs仍然占VC内暗物质粒子的23%（接近观测到的偏离红序列的星系团星系的比例）。最佳拟合投影NFW/Einasto模型在速度切割后（前）低估了3D浓度的6+/-6%（16+/-7%），除非在拟合中包括一个恒定背景。假设正确的质量剖面，从测量的LOSVDP中可以很好地恢复VA剖面，在外区有轻微的偏向更径向轨道的偏差。这些小偏差被由宇宙变化引起的星系团间的大变化所掩盖。附录提供了Einasto模型的表面密度、投影质量和切向剪切剖面的解析近似。 显示英文摘要

摘要： When clusters of galaxies are viewed in projection, one cannot avoid picking up foreground/background interlopers (FBIs), that lie within the virial cone (VC), but outside the virial sphere. Structural & kinematic deprojection equations are not known for an expanding Universe, where the Hubble flow (HF) stretches the line-of-sight (LOS) distribution of velocities. We analyze 93 mock relaxed clusters, built from a cosmological simulation. The stacked mock cluster is well fit by an m=5 Einasto DM density profile (but only out to 1.5 virial radii [r_v]), with velocity anisotropy (VA) close to the Mamon-Lokas model with VA radius equal to that of density slope -2. The surface density of FBIs is nearly flat out to r_v, while their LOS velocity distribution shows a dominant gaussian cluster-outskirts component and a flat field component. This distribution of FBIs in projected phase space is nearly universal in mass. A local k=2.7 sigma velocity cut returns the LOS velocity dispersion profile (LOSVDP) expected from the NFW density and VA profiles measured in 3D. The HF causes a shallower outer LOSVDP that cannot be well matched by the Einasto model for any k. After this velocity cut, FBIs still account for 23% of DM particles within the VC (close to the observed fraction of cluster galaxies lying off the Red Sequence). The best-fit projected NFW/Einasto models underestimate the 3D concentration by 6+/-6% (16+/-7%) after (before) the velocity cut, unless a constant background is included in the fit. Assuming the correct mass profile, the VA profile is well recovered from the measured LOSVDP, with a slight bias towards more radial orbits in the outer regions. These small biases are overshadowed by large cluster-cluster variations caused by cosmic variance. An appendix provides an analytical approximation to the surface density, projected mass and tangential shear profiles of the Einasto model.