LSST-DESC 预研项目：谐波空间中的超新星相机第一年 3×2pt 分析
An LSST-DESC Precursor Project: Hyper Suprime-Cam Year 1 $3\times2$pt in Harmonic Space
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中文总结 AI 辅助
该预研项目在谐波空间对 HSC Y1 数据实现全测光 3×2pt 联合分析，验证 DESC 流程，并给出 ΛCDM 约束 Ω_m=0.249、σ_8=0.904、S_8=0.821，为 LSST 第一年分析奠基。
中文摘要 AI 辅助
我们首次展示了利用 LSST-DESC 分析流程，对超新星相机第一年（HSC Y1）数据在谐波空间中进行的弱引力透镜与星系成团性的全测光联合分析（3×2pt）。HSC Y1 数据集的成像深度和星系数密度与 LSST 观测第一年预期值相近，是验证 DESC 测量与推断工具的理想试验场。我们测量了完整的角功率谱集合——宇宙剪切、星系成团性和星系-星系透镜——进行了零检验，并通过模式去投影校正了观测条件对星系密度场和剪切场的影响。我们通过使用 DESC 推断代码重现官方 HSC Y1 宇宙剪切宇宙学约束，验证了我们的似然流程。联合分析所有三个两点函数，我们约束了 ΛCDM 和 wCDM 宇宙学，报告了宇宙剪切、星系成团性与星系-星系透镜组合（2×2pt）以及完整 3×2pt 的结果。从联合 3×2pt ΛCDM 分析中，我们得到 Ω_m = 0.249^{+0.061}_{-0.051}，σ_8 = 0.904^{+0.098}_{-0.091}，以及 S_8 ≡ σ_8√(Ω_m/0.3) = 0.821^{+0.018}_{-0.021}。该分析在巡天数据上验证了完整的 DESC 3×2pt 基础设施，为即将进行的 LSST 第一年宇宙学分析奠定了基础。
英文摘要
We present the first fully photometric joint analysis of weak gravitational lensing and galaxy clustering (3$\times$2pt) in harmonic space with LSST-DESC analysis pipelines applied to Hyper Suprime-Cam Year 1 (HSC Y1) data. The HSC Y1 dataset, with imaging depth and galaxy number density similar to those expected for the first year of LSST observations, is an ideal testbed for validating DESC measurement and inference tools. We measure the full set of angular power spectra - cosmic shear, galaxy clustering, and galaxy-galaxy lensing - perform null tests, and correct for the impact of observing conditions on both the galaxy density and shear fields via mode deprojection. We validate our likelihood pipeline by reproducing the official HSC Y1 cosmic shear cosmological constraints with the DESC inference code. Jointly analysing all three two-point functions, we constrain $Λ$CDM and $w$CDM cosmologies, reporting results for cosmic shear, the combination of galaxy clustering and galaxy-galaxy lensing (2$\times$2pt), and the full 3$\times$2pt. From the joint 3$\times$2pt $Λ$CDM analysis we find $Ω_m = 0.249^{+0.061}_{-0.051}$, $σ_8 = 0.904^{+0.098}_{-0.091}$, and $S_8 \equiv σ_8\sqrt{Ω_m/0.3} = 0.821^{+0.018}_{-0.021}$. This analysis validates the complete DESC 3x2pt infrastructure on survey data, providing the foundation for the forthcoming LSST Year 1 cosmological analysis.
