arXiv:2601.17222astro-ph.IMastro-ph.CO2026-01中稿 · publication in AJ被引 2

用多源数据训练模型,提升星系红移预测的准确性与可靠性。

Improving Generalization and Uncertainty Quantification of Photometric Redshift Models

  • 融合光谱与多波段测光数据构建混合训练集
  • 红移0.3到1.5区间偏差降低4.5倍,异常值率降1.4倍
  • 适用于欧几里得、LSST等大型巡天项目

精确的红移估计对理解星系演化和精密宇宙学至关重要。本文探讨了提升机器学习模型在更广泛星系类型上适用性的方法。传统模型基于光谱观测的真实红移进行训练,而本文测试了两种结合光谱红移与多波段(约35个滤镜)测光红移的方法:(1)在复合数据集上训练;(2)跨数据集迁移学习。我们整合了COSMOS2020星表中的测光红移(TransferZ),补充已有的光谱红移数据集(GalaxiesML)。采用确定性神经网络(NN)和贝叶斯神经网络(BNN)两种架构,评估其满足未来太空与时间调查(LSST)光谱红移科学需求的表现。同时使用分拆合取预测校准不确定性估计,分别为BNN和NN生成预测区间。结果表明,基于复合数据集训练的神经网络,在红移0.3<z<1.5范围内误差降低4.5倍,离散度减少1.1倍,异常值率下降1.4倍;贝叶斯模型能提供可靠不确定性估计,但对真实标签来源敏感。该研究利用多源真实红移数据,发展出可准确预测更广泛星系群体红移的模型,对欧几里得、LSST等巡天项目具有重要意义。

原文摘要 · Abstract (English)

Accurate redshift estimates are a vital component in understanding galaxy evolution and precision cosmology. In this paper, we explore approaches to increase the applicability of machine learning models for photometric redshift estimation on a broader range of galaxy types. Typical models are trained with ground-truth redshifts from spectroscopy. We test the utility and effectiveness of two approaches for combining spectroscopic redshifts and redshifts derived from multiband ($\sim$35 filters) photometry, which sample different types of galaxies compared to spectroscopic surveys. The two approaches are (1) training on a composite dataset and (2) transfer learning from one dataset to another. We compile photometric redshifts from the COSMOS2020 catalog (TransferZ) to complement an established spectroscopic redshift dataset (GalaxiesML). We used two architectures, deterministic neural networks (NN) and Bayesian neural networks (BNN), to examine and evaluate their performance with respect to the Legacy Survey of Space and Time (LSST) photo-$z$ science requirements. We also use split conformal prediction for calibrating uncertainty estimates and producing prediction intervals for the BNN and NN, respectively. We find that a NN trained on a composite dataset predicts photo-$z$'s that are 4.5 times less biased within the redshift range $0.3<z<1.5$, 1.1 times less scattered, and has a 1.4 times lower outlier rate than a model trained on only spectroscopic ground truths. We also find that BNNs produce reliable uncertainty estimates, but are sensitive to the different ground truths. This investigation leverages different sources of ground truths to develop models that can accurately predict photo-$z$'s for a broader population of galaxies crucial for surveys such as Euclid and LSST.

红移估计机器学习宇宙学不确定性量化

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