发表机构
Scuola Normale Superiore; University of Catania; Stellenbosch University（比萨高等师范学院; 卡塔尼亚大学; 斯坦陵布什大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本文提出混合机器学习流程TILING，结合点估计与扩散网络，利用星系图和21厘米观测在再电离时期重建宇宙学初始条件，实现高精度重建并指导后续观测。
AI 中文摘要
重建观测体积内物质场的初始条件（ICs）可提供该区域时间演化的完整图景。初始条件重建在低红移处较为常见，但在再电离时期（EoR；$z\gtrsim 5$）尚未充分探索，部分原因在于对非均匀宇宙辐射场建模的困难。然而，再电离时期覆盖了可观测宇宙的一半，为天体物理学和宇宙学提供了无与伦比的潜力。在此，我们量化了即将开展的星系和21厘米观测在再电离时期约束初始条件的能力。我们开发了TILING（通过网络嫁接对线性初始条件进行层析推断）：一种混合机器学习流程，首先产生初始条件的点估计，随后改进基于分数的扩散网络以生成后验样本。我们在不同紫外极限星等下的模拟星系图，以及不同噪声水平和前景“楔形”污染下的相应21厘米图上训练TILING。对于基准巡天选择，我们实现了精确的初始条件重建（后验均值互相关系数>0.8，功率谱误差在几个百分点以内），直至$\text{k}\lesssim 0.2 \text{cMpc}^{-1}$。虽然21厘米干涉测量有助于恢复初始条件功率谱，但大部分约束能力，尤其是对初始条件傅里叶相位，来自星系图，这强调了在解释21厘米信号时进行互补观测的必要性。我们展示了TILING如何恢复被前景污染切除的21厘米功率谱模式。我们的框架还可：（i）指导对感兴趣子体积的后续观测；（ii）重建特定体积的星系演化和再电离形态；（iii）分离光学/红外望远镜（如JWST）无法观测的绝大多数星系对再电离的贡献。我们的代码公开可用。
英文摘要
Reconstructing the initial conditions (ICs) of the matter field for an observed volume gives a complete picture of that region's temporal evolution. IC reconstruction is common at low redshifts but largely unexplored during the epoch of reionization (EoR; $z\gtrsim 5$), partly due to difficulties modeling inhomogeneous cosmic radiation fields. Yet the EoR spans half the observable Universe, offering unmatched potential for astrophysics and cosmology. Here we quantify how well upcoming galaxy and 21cm observations can constrain ICs during the EoR. We develop $\tt TILING$ ($\bf T$omographic $\bf I$nference of $\bf L$inear $\bf I$Cs via $\bf N$etwork $\bf G$rafting): a hybrid machine learning pipeline that first produces a point estimate of the ICs, which then improves a score-based diffusion network for generating posterior samples. We train $\tt TILING$ on mock galaxy maps at varying UV magnitude limits, plus corresponding 21cm maps at varying noise levels and foreground "wedge" contamination. For fiducial survey choices, we achieve accurate IC reconstruction (posterior mean cross-correlation coefficients >0.8 and power spectrum errors under a few percent) down to $\text{k}\lesssim 0.2 \text{cMpc}^{-1}$. While 21cm interferometry aids recovery of IC power spectra, most constraining power, especially for IC Fourier phases, comes from galaxy maps, underscoring the need for complementary observations when interpreting the 21cm signal. We show how $\tt TILING$ can recover 21cm power spectrum modes excised by foreground contamination. Our framework can also: (i) guide follow-up observations of sub-volumes of interest; (ii) reconstruct galaxy evolution and reionization morphology for specific volumes; and (iii) isolate the contribution to reionization from the vast majority of galaxies unobservable by optical/IR telescopes like $\it JWST$. Our code is publicly available.
Comments22 pages, 17 figures, 2 tables
