发表机构
Laboratory of High Energy and Computational Physics, KBFI; Tallinn University of Technology（高能计算物理实验室，KBFI; 塔尔图理工大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出改进的弱透镜放大率随机模型并开发FLUMEN神经仿真器，快速预测放大率分布，与晕模型一致，为宇宙学分析提供高效框架。
AI 中文摘要
弱引力透镜由 intervening structure 引起，会放大遥远源并导致其光度距离产生散射。我们开发了一个改进的弱引力透镜放大率分布 $\textrm{d} P/\textrm{d}\mu$ 的随机模型，该模型可解析到 $10^7\\,M_\odot$ 的单个透镜体，并且除了场晕和丝状结构外，还包含了子晕和透镜群体的大尺度成团性。这两种扩展都加宽了分布，由此产生的光度距离散射与非线性物质功率谱的晕模型预测一致，并超过了从 $N$ 体光线追踪获得的结果，我们将其归因于模拟的有限质量分辨率和盒子尺寸。基于此模型，我们开发了 \texttt{FLUMEN}，一个条件归一化流仿真器，它预测 $\textrm{d} P/\textrm{d}\mu$ 作为源红移（最高至 $z_s=12$）和六个宇宙学参数 $\{h,\Omega_M,\Omega_B,\sigma_8,n_s,z_{\rm eq}\}$ 的函数。该仿真器解析地强制了空光束截止和折叠焦散幂律尾部，并在保留的宇宙学参数上以中位 Kullback--Leibler 散度 $0.0048$ 且几乎零成本地重现了蒙特卡洛分布。我们的结果为将完整的放大率分布纳入标准汽笛、超新星和其他点源的宇宙学分析提供了一个快速且灵活的框架。
英文摘要
Weak gravitational lensing by intervening structure magnifies distant sources and induces scatter in their luminosity distances. We develop an improved stochastic model for the distribution of weak lensing magnifications, $\textrm{d} P/\textrm{d}μ$, that resolves individual lenses down to $10^7\,M_\odot$ and, besides field halos and filaments, includes subhalos and large-scale clustering of the lens population. Both extensions broaden the distribution, and the resulting scatter in the luminosity distances agrees with the halo-model prediction from the nonlinear matter power spectrum and exceeds that obtained from $N$-body ray tracing, which we attribute to the finite mass resolution and box size of the simulations. Building on this model, we develop \texttt{FLUMEN}, a conditional normalizing-flow emulator that predicts $\textrm{d} P/\textrm{d}μ$ as a function of the source redshift up to $z_s=12$ and six cosmological parameters $\{h,Ω_M,Ω_B,σ_8,n_s,z_{\rm eq}\}$. The emulator enforces the empty-beam cutoff and the fold-caustic power-law tail analytically, and reproduces the Monte Carlo distributions on held-out cosmologies with a median Kullback--Leibler divergence of $0.0048$ at negligible cost. Our results provide a fast and flexible framework for incorporating the full magnification distribution into cosmological analyses of standard sirens, supernovae, and other point sources.
Comments14 pages, 12 figures + Appendix. Git link: https://github.com/baltabaygal/flumen
