论文标题
在大量中微子存在下的拉格朗日扰动理论
A Lagrangian Perturbation Theory in the presence of massive neutrinos
论文作者
论文摘要
我们开发了一种拉格朗日扰动理论（LPT）框架，以研究具有大量中微子的宇宙学中冷暗物质（CDM）的聚类。我们遵循扰动理论中最高三阶的拉格朗日位移的CDM颗粒的轨迹。一旦中微子成为非相关主义，它们的密度波动被建模为与CDM密度波动成正比，具有比例依赖性的比例因子。这产生了引力后反应，该反应将额外的量表引入了线性生长函数，该函数以较高的LPT内核来解释。通过从Eulerian到Lagrangian框架的非线性映射，我们确保我们的理论具有良好的大规模行为，没有不需要的紫外线差异，当中微子和CDM密度不相等时，这很常见，并且在同等的基础上进行治疗，并且在重新启示的方案中显然会破坏了耗电的不变性。我们使用理论来构建基本物质领域以及使用卷积lpt的有偏见的示踪剂的相关函数。红移空间扭曲效果是使用高斯流媒体模型建模的。将我们的分析结果与来自Quijote Simulation Suite的模拟数据进行比较时，我们发现良好的精度降至$ r = 20 \，\ text {mpc} \，H^{ - 1} $在redshift $ z = 0.5 $上，用于真实空间和无免费参数的真实空间和无免费参数。如果我们还考虑一个有效的场理论参数，它可以达到红移空间四极的精度，该参数会移动成对速度分散。为了建模示踪剂的相关函数，我们仅使用密度和曲率运算符采用一个简单的拉格朗日偏置方案，我们发现在比较与模拟的晕筒时，我们发现足以触及到$ r = 20 \，\ text {mpc} \，h^{ - 1} $。
We develop a Lagrangian Perturbation Theory (LPT) framework to study the clustering of cold dark matter (CDM) in cosmologies with massive neutrinos. We follow the trajectories of CDM particles with Lagrangian displacements fields up to third order in perturbation theory. Once the neutrinos become non-relativistic, their density fluctuations are modeled as being proportional to the CDM density fluctuations, with a scale-dependent proportionality factor. This yields a gravitational back-reaction that introduces additional scales to the linear growth function, which is accounted for in the higher order LPT kernels. Through non-linear mappings from Eulerian to Lagrangian frames, we ensure that our theory has a well behaved large scale behavior free of unwanted UV divergences, which are common when neutrino and CDM densities are not treated on an equal footing, and in resummation schemes that manifestly break Galilean invariance. We use our theory to construct correlation functions for both the underlying matter field, as well as for biased tracers using Convolution-LPT. Redshift-space distortions effects are modeled using the Gaussian Streaming Model. When comparing our analytical results to simulated data from the Quijote simulation suite, we find good accuracy down to $r=20 \,\text{Mpc} \, h^{-1}$ at redshift $z=0.5$, for the real space and redshift space monopole particle correlation functions with no free parameters. The same accuracy is reached for the redshift space quadrupole if we additionally consider an effective field theory parameter that shifts the pairwise velocity dispersion. For modeling the correlation functions of tracers we adopt a simple Lagrangian biasing scheme with only density and curvature operators, which we find sufficient to reach down to $r=20 \,\text{Mpc} \, h^{-1}$ when comparing to simulated halos.
